Balancing GURPS Combat: Odds to Hit

One of the keys to being a confident GURPS GM is to understand how to create combat encounters that are balanced to the party’s abilities. This post will look at a critical element of combat balance: how likely each side is to land blows. GMs should consider the defensive abilities of the combatants when evaluating how challenging an encounter will be.

Start With Defense

It doesn’t matter how much damage an attack can deal if the blow never lands. Unless the attacker rolls a critical success, the defender gets to attempt a defense roll. As a result, defensive skill is extraordinarily important.

The table below shows the chances of landing a hit based on the effective skills of the attacker and defender. The first thing you should notice is that the attacker’s skill makes a big difference when the defender’s skill is low. However, once the defender’s effective skill gets above 10, most attackers will eek out a hit only one out of three attempts, at best.

Odds to Hit for Effective Attack vs Defense Skills
Odds to Hit for Effective Attack vs Defense Skills

So, when judging how difficult a combat encounter is, the first question should be: how well can each side defend? If the player characters are facing an opponent that has a base active defense skill above 10, they need to have ways to lower the effective defense skill in order to expect to land blows with any regularity. Conversely, if the players have a high active defense skill, the opponents should have ways to lower the effective skill in order to put the characters into jeopardy.

When Defense Isn’t Enough

Defense skills are important for balancing combat, but there are some situations in which even the best defensive skills aren’t enough:

  • Lethal damage: if an attack can do lethal damage with a single blow, then a high defense skill doesn’t eliminate the risk—it just makes the outcome a high-stakes gamble. A single good (or bad) dice roll can radically change the result, so the GM needs to be prepared to handle the worst.
  • Area effects: when an attack targets a large area, there may be no active defense possible. Area effects may give PCs a way to take down NPCs with extremely high active defense skills, but opponents can also use these effects to circumvent player defenses.
  • Mental attacks: Physical defenses are useless against mental assaults. If a character can terrify an opponent, manipulate their senses, or otherwise get inside their antagonist’s head, the GM should think about how that will play out in combat.
  • Surprise attacks: Finally, active defenses are useless if the target never sees the attack coming. The players (or NPCs) can make tactical decisions to give themselves the element of surprise during the combat, but the GM should also think about whether one side can set up an ambush before the battle is joined.

Estimating GURPS Skill Levels

GURPS is a skill-based roleplaying game. If you understand how skill levels work mechanically, you can run or play a game. It’s easy to lose sight of the skill system because GURPS has elaborate options for character customization. But, if you’re feeling overwhelmed, you can always strip the system back to skills in order to create a manageable gaming experience.

The GURPS Skill Triangle

In play, GURPS skills are driven by three factors: the base skill level, the effective skill level, and the task difficulty modifiers. These three elements make up what I call the GURPS Skill Triangle. If you understand how the Triangle is put together, you can easily improvise challenges in GURPS.

Base Skill Level

The base skill level is what level the character has listed for a skill on their character sheet. The Basic Set gives the following descriptions for what base skill levels represent (paraphrasing from p. B172):

  • Ordinary folks have base skill levels ranging from 8 to 13. Skills important to the character’s profession tend to be at level 12 or 13; rarely used skills are often at level 8 or 9.
  • Experts have skill levels that go higher. In general, even a master in the field will usually max out a specific skill at 20 or 25, preferring to study complimentary skills instead of pushing an elite skill above level 25.

Base skill levels below 10 are poorly known skills; the character can succeed at the task on occasion or with aid, but frequently struggles with the ability. At skill levels 10 or 11, the character is more often successful but their abilities are still inconsistent. At level 12, skills are solid enough to cover most occupational demands (whether that be swinging a sword, negotiating a settlement, or navigating a bureaucracy). And, at levels 14 and above, the person demonstrates mastery of their ability.

Task Difficulty Modifiers

Of course, some tasks are more difficult than others. The second leg of the Triangle, task difficulty modifiers, is a catch-all for the situational modifiers that apply to a given success roll. This can include bonuses for using complimentary skills or easier-than-average conditions, penalties for poor equipment or working at a different tech level—anything that changes the odds of success. GURPS has rules that codify the modifiers for a variety of situations, but GMs can also use generic task difficulty modifiers to indicate that a task is more or less challenging.

The default task difficulty, +0, represents using the skill under normal adventuring conditions. Ordinary, everyday situations are less stressful and therefore get bonuses to reflect the less challenging circumstances. By contrast, tasks that would give pause to even brave adventurers receive task difficulty penalties in order to reflect the challenge of the situation.

Basic Set pp. B345–B346 describes the range of typical task difficulties, from +10 (automatic success except for flukes of chance) all the way to -10 (impossible tasks that no sane person would attempt).

Effective Skill Level

The third side of the Triangle, effective skill level, is the result of combining the other two sides. The base skill level + the sum of all the relevant task difficulty modifiers results in the effective skill level.

Players make success rolls against the effective skill level of their character, so effective skill levels correspond directly to the chances of success (the full table is listed on p. B171):

  • Below effective skill 8, the odds of success are 16.2% or less (depending on the specific skill level).
  • Effective skill 8 will succeed 25.9% of the time.
  • Effective skill 9 will succeed 37.5% of the time.
  • Effective skill 10 will succeed 50% of the time.
  • Effective skill 11 will succeed 62.5% of the time.
  • Effective skill 12 will succeed 74.1% of the time.
  • The odds of success continue increasing for each additional skill level, albeit at a smaller rate as the levels increase.
  • Once a character hits an effective skill of 16, their success is capped at 98.1% (because of the fixed chance of rolling a failure or critical failure).

Using the Triangle

Because all three sides of the Triangle are connected, GMs can manipulate the Triangle in order to produce the results that a game situation demands.

Let’s say that a PC wants investigate a crime scene. The base skill level is set: just read the character sheet to see what the PC has for Investigation. The GM can set the task difficulty modifier based on how complex the scene is, which will produce the effective skill level for that situation.

But, the GM can also work backwards. Let’s say that, for narrative reasons, the GM wants the PC to have just slightly better-than-even odds of finding a specific clue. Perhaps the GM wants to reward the PCs for finding some leads earlier (which narrow down the search) but still wants to emphasize that the PCs don’t have the whole story. In that case, the GM can use the Triangle to figure out how to create the desired effective skill level of 11. If the PC has a base skill of Investigation-15, the GM needs to describe the situation in order to justify a task difficulty modifier of -4. The GM could therefore describe the apparent disorder of the scene, the lack of immediately obvious signs, or the short amount of time the PCs have until the cops arrive and kick them out of the scene.

The GM can keep working backwards through the Triangle in order to flesh out the relevant NPCs. Suppose the player characters are trying to track a bandit through the forest. The players know the task difficulty modifier for that situation: -4 because of poor weather and unfamiliar terrain. If they fail, but they encounter a ranger who can hunt down the bandit easily, it’s clear that the ranger has a much higher base skill because he can absorb the tracking penalties and still have a high effective skill level.  The PCs may want to befriend this ranger in order to take advantage of his superior talents!

On the other hand, the Triangle can be used to show that the NPCs aren’t as skilled as the players might expect. If the PCs observe a mage working a ritual, and the mage surrounds herself with lots of props in order to power the ritual but still barely eeks out a successful casting, that tells the players that the mage had a relatively low effective skill despite a high bonus for the task difficulty, which implies that she has a low base skill for ritual magic. If the players are normally cautious, this kind of information about the mage can help them assess how dangerous she would be when cornered.

Quick-and-Dirty Skill Levels

Finally, the GM can take advantage of the Triangle to simplify non-player character building. Instead of figuring out what skill levels NPCs should have before the game, the GM can use the Triangle to come up with plausible character stats on the fly.

Because the three sides of the Triangle are linked, the GM can use any two of the three elements to estimate the third side. An NPC should probably succeed on a task? Assume the NPC has an effective skill of 14, determine how difficult the task is, and then derive the base skill level from those two factors. Or, if the NPC has a base skill already established but he or she should likely fail at a task in this situation, work out the task difficulty modifiers so that his or her effective skill is 8 or less.

Applying the Skill Triangle

GURPS often requires GM judgment. By understanding the Skill Triangle, GMs can check their ballpark estimates to make sure that their judgment calls fit the game. Is a task penalty too harsh? Check what effect it has on the odds of success for the new effective skill. Is a base skill level too low for the campaign? Ask what kind of difficulty penalties the character will have to deal with on a regular basis, and see whether the resulting effective skill level is high enough to challenge the players without overwhelming them. Are the characters being challenged enough? Look at what their effective skill is, and adjust the task difficulty modifiers until the players feel a genuine sense of risk.

The Triangle enables GMs to check their work by comparing the game mechanics to the narrative descriptions those mechanics represent. If one side of the Triangle is out of whack, the GM can refine the mechanics until all the elements make sense together.


Faster Combat by Pre-Rolling Dice

Dice in cigar boxGURPS combat uses a lot of dice rolls. In addition to attacks and damage rolls, GURPS uses rolls for active defenses, skill checks to handle difficult terrain or maintain concentration, and even morale checks to determine if enemies will flee.

Good GMs know that it is important to keep combat moving in order to maintain player engagement. One way to maintain the focus on the player’s decisions is to streamline NPC time. With all the dice rolls in combat, one easy way to spend less time resolving NPC actions is to pre-roll the dice for NPCs.

Rolling in Advance

When players roll the dice, it’s exciting! They want to find out the result of their actions. Every roleplayer will have memories of phenomenal rolls that snatched victory from the jaws of defeat—or embarrassing recollections of a truly unlucky roll at the worst possible moment.

Waiting for NPCs to resolve their actions is less interesting. The players want to know what happened, but the suspense of figuring out the dice roll is far less engaging. And, if the players spend too much time waiting for NPCs to finish, they become bored.

While rolling and adding up dice can be time-consuming in game, there’s no reason that the GM has to spend that time during the game. The GM can instead pre-generate a sequence of dice rolls and simply refer to that list during the game.

How to Pre-Roll

The easiest way to generate a list of dice rolls is to use a digital dice roller and record the results in the order they were rolled. Because all success rolls in GURPS use 3d6, the GM can create a list of 3d6 roll results. Then, whenever the GM needs a success roll for an NPC, he or she can look up the next result on the list, use that number, and cross it off. As long as the dice roller is random, there’s no functional difference between rolling in the moment and using the very next entry in a pre-generated list.

There’s one caveat: the GM can’t look at the number before deciding what the NPC will do! The NPC doesn’t have foreknowledge and so the GM shouldn’t be able to strategically choose the skill or modifiers in order to ensure a success (or failure). The GM needs to choose the action, determine the effective skill level, and only then look at the list. The GM also has to take the very next number; it’s no fair skipping around to avoid a critical hit or miss!

This technique can be expanded for other common rolls. For instance, if many NPCs will be making 2d damage rolls, the GM can generate a separate list of 2d results. However, the biggest payoff comes from the 3d6 list because the vast majority of GURPS rolls use 3d6.

Creating Pre-Rolled Lists in Excel

List of pre-rolled 3d6 results in Microsoft Excel

If you have Microsoft Excel, you can easily create lists of pre-rolled dice results. Other spreadsheet programs will have similar functions, but you may need to adjust the formula to match the program’s function names.

In Excel, create a new spreadsheet and select a blank cell. Then, use Excel’s built-in random number generator to roll three dice by copying and pasting the the following formula:


The RANDBETWEEN function generates a random number between the two bounding numbers, so RANDBETWEEN(1,6) is equivalent to rolling a single d6. Since we want to roll 3d6, we use that formula three times and add them together.

From there, we can copy and paste that formula into additional cells until we have enough results. Note that each time you change a cell (including pasting this formula into a new cell), Excel will recalculate all the formulas in the spreadsheet. So, you’ll see the numbers change as long as you are building the sheet. That’s fine. Just print out the spreadsheet when you’re done, and use those numbers.

If you want to roll a different set of dice, you can do so by changing the formula. If you decide to roll damage, remember that GURPS does not allow damage to go below 1 (for crushing damage, below 0). You can use the MAX function to impose a lower bound on the result. For example, to calculate 1d-3 piercing damage, you can use the formula below:


Blog-or-Treat: Simplified Fright Checks

Halloween is coming soon, and GURPS can help you add a little horror to your roleplaying campaign! Almost any game can add elements of horror in order to deepen the experience. We’re used to seeing stories add humor to lighten things up with comic relief; the same principle can work in the other direction. GURPS provides a specific mechanic to help establish that a situation is dangerous: fright checks.

Horror stories often feature vulnerability or helplessness on the part of the protagonists, fear, and uncertainty. In the full-blown horror genre, these elements can dominate the story. But, when added in small doses, they provide contrast to show just how heroic the characters are. After all, heroes are more impressive when they rise above terrifying circumstances and succeed despite great personal risk.

Using Fright Checks

Image from the Fright Check Table in GURPS Basic Set
Image from the Fright Check Table in GURPS Basic Set

One of the easiest ways to add a horror element to your games is to include fright checks. When faced with scary, risky, or just plain dangerous situations, ask the players to make a fright check in order to proceed—or suffer the consequences from putting their necks on the line!

Fright checks are described in the Basic Set, pp. B360–B361. The core concept is simple: when characters face a fear-inducing situation, they must make a Will-based success roll. If the player succeeds at the roll, the character can act normally. However, a failed fright check indicates that the character was overwhelmed by fear, and as a result suffers a setback ranging from being stunned to suffering traumatic mental injury.

What should trigger a fright check? It depends on your campaign premise and the characters, but the general idea is things that are unusually scary—not just ordinary adventuring experiences. In a warfare campaign going over the top of a trench into enemy machine guns qualifies. In a fantasy campaign, the GM could call for a fright check when encountering a primordial evil beast. For an action and adventure campaign, the moment in which the protagonists realize how outnumbered they are could justify a fright check.

Because fright checks are success rolls, the GM can streamline fright checks by assigning a generic task difficulty modifier instead of looking up and synthesizing a list of individual modifiers. That’s it! Just choose a modifier that represents how fear-inducing the situation is, make a Will-based roll, and narrate the result like any other success roll.

Rule of 14

One of the ways that fright checks can differ from generic success rolls in the Rule of 14. The GM can choose to invoke the Fright Check Rule of 14 to cap effective skill at 14. No matter how strong a character’s will is, there’s always a small chance of failing a fright check.

The Fright Check Rule of 14 is, like all of GURPS, an optional rule. The rule exists primarily for storytelling reasons rather than as a mechanical requirement. In short, one of the tropes of horror is that any character can be overcome with terror in a stressful circumstance. While most RPG genres emphasize the competence of the PCs, horror needs to balance PC agency with vulnerability. If a character is entirely immune to terror, it takes away a lot of the suspense. So, the Rule of 14 ensures that there is always a roughly 1-in-10 chance of failure.

In non-horror genres, the Fright Check Rule of 14 may be inappropriate. For instance, a four-color hero might have an exceptional will and narratively wouldn’t be overcome with fear. Likewise, a supernatural monster hunter campaign might feature a protagonist that stands out because of his or her preternatural calm in the face of the macabre. And, the GM can make the Rule of 14 irrelevant by using larger task difficulty modifiers when necessary. As a result, the Fright Check Rule of 14 is not necessary when requiring fright checks.

Failing Fright Checks

The most unique (and therefore most confusing) part of fright checks is the mechanic for resolving failed fright checks. The good news is that, again, it’s an optional mechanic. Just like a GM can ignore the critical miss table and narrate their own result for a critical miss on an attack roll, the GM can narrate their own consequence for a failed fright check roll.

The official mechanic for failed fright checks uses two rolls. The first is the original success roll. The player takes their margin of failure from this roll. The second element is an extra 3d6 roll. The player adds these two numbers—the margin of failure and the separate 3d6 roll—and looks up the sum on the Fright Check table.

Higher totals lead to worse consequences for the failed fright check. So, the margin of failure matters. However, the separate roll adds a substantial random element. As a result, it’s possible for a narrow failure to result in moderately severe consequences. Conversely, it may be possible for a player to escape from even a horribly failed roll with nothing more than a minor setback.

The choice to use two rolls seems driven by genre conventions rather than mechanical requirements. Unpredictability is a trademark of the horror genre, so the outside possibility of a serious disaster even for relatively narrow failures adds to the suspense. But, because there’s not a mechanical need to have a second roll, there’s no inherent problem with the GM ignoring the Fright Check table and instead determining their own result.

Ballparking Damage in GURPS

In the heat of combat, the last thing you want to do is pause to look up a a rule. GURPS has detailed weapon statistics that players can write on their character sheets before the game, but sometimes the GM needs to improvise. The PCs accidentally alerted the night watch and you need a polearm’s damage? A character turns a length of rope into a makeshift lasso? When the GM needs to come up with damage numbers on the fly, it can be helpful to make a ballpark estimate of how much damage an attack should generate.

This post provides order-of-magnitude estimates for how much damage weapons do. This is a deliberate oversimplification meant to give GMs guidance when figuring out reasonable estimates: it rounds numbers from the Basic Set, skips over rules in supplement volumes, and doesn’t look at special kinds of damage like armor divisors, fragmentation, and cyclic damage. Using this scale, GMs can choose damage rolls that pass the eyeball test.

Damage Roll Estimates

1d-3: Attacks that deal this level of damage are minor. When relevant, any kind of armor can absorb this magnitude of damage. Any injury that gets through won’t have much effect unless the character is damaged repeatedly.

  • Bite (average strength)
  • Fire (momentary exposure)
  • Poison (mild)
  • Punch (average strength)

1d-2: This category is a little more dangerous. Weak armor may not absorb all the damage, but the injury isn’t usually severe on its own.

  • Bite (above-average strength)
  • Kick (average strength)
  • Punch (above-average strength)

1d-1: This level of damage starts to leave an impact. A high roll can take out nearly half of a character’s HP without protection, and multiple hits will quickly accumulate the injury even under the best of circumstances.

  • Bow (average strength)
  • Fire (sustained exposure)
  • Kick (above-average strength)
  • Knife (average strength)

1d: Attacks at this level can knock out a normal, unarmored human in two hits! Even a single hit can cripple a limb or cause major injury.

  • Bite (extraordinary strength)
  • Bow (above-average strength)
  • Knife (above-average strength)
  • Longbow (average strength)
  • Poison (strong, e.g. arsenic)
  • Punch (extraordinary strength)

1d+1: Armor is almost mandatory to withstand these attacks. Unprotected characters can expect to lose limbs or collapse from shock.

  • Axe (average strength)
  • Bow (extraordinary strength)
  • Crossbow (average strength)
  • Kick (above-average strength)
  • Longbow (above-average strength)
  • Spear (average strength)
  • Sword (average strength)

2d: These attacks can fell an unprotected human in a single blow, and even armored characters will be in trouble if they suffer multiple attacks!

  • Axe (above-average strength)
  • Crossbow (above-average strength)
  • Knife (extraordinary strength)
  • Longbow (extraordinary strength)
  • Poison (severe, e.g. cobra venom)
  • Quarterstaff (average strength)
  • Spear (extraordinary strength)
  • Sword (above-average strength)

3d: At this level, even basic armor may not be enough to keep a character alive. Unarmored characters will need a great deal of luck to withstand an attack and continue functioning.

  • Axe (extraordinary strength)
  • Crossbow (extraordinary strength)
  • Flamethrower
  • Grenade (powder)
  • Machine gun
  • Quarterstaff (extraordinary strength)
  • Revolver

4d: Unless you are extraordinarily well protected and lucky, your character is out of the battle once one of these blows lands.

  • Grenade (fragmentation)
  • Laser weapon
  • Poison (deadly, e.g. cyanide)
  • Rifle

Beyond 4d: Attacks that do more than 4d damage tend to be either superscience weapons, futuristic technology, or weapons designed for heavy targets rather than attacking individuals. You can scale the numbers as large as needed, but it may make more sense to give the weapon an armor divisor or affliction rather than just increasing the numbers.


In the examples above, “average,” “above average,” and “extraordinary” refer to the human norm (specifically ST levels of 10, 12, and 15). It’s not uncommon for realistic animals to reach ST levels of 20, and of course fictional creatures can have far higher strength levels. In those cases, extrapolate as necessary!

The damage rolls were chosen based on the GURPS logarithmic progression. GURPS uses a six step progression in several places, most notably the Size/Speed/Range table, to scale modifiers among several orders of magnitude. The progression goes: 1, 1.5, 2, 3, 5, 7, 10, and then repeats with the new order of magnitude as the base level (so 10*1.5 = 15, 10*2 = 20, etc.). The damage rolls listed yield an average damage that roughly tracks this progression.

Aborting Combat in GURPS

Balancing combat in GURPS can be challenging, especially for new GMs. Running combat encounters is much easier when the GM knows how to abort a battle that is overwhelming the player characters.

Sometimes, the players deliberately bite off more than they can chew; in those cases, it makes sense for the battle to carry a lot of risk, and the GM is justified in letting the players suffer the total party kill that they have brought upon themselves. But most of the time, TPKs emerge by accident; the GM miscalculates what the PCs can handle, and the resulting carnage is a serious disappointment. GMs therefore want to minimize the risk of accidentally annihilating the party.

There are some obvious ways to bail from combat if an encounter is too deadly: having the NPCs suddenly pull their punches, adjusting stats on the fly, or fudging dice rolls. However, these actions can leave both the GM and players feeling cheated. It’s nice to avoid a total party kill, but it’s better to not put the players into that situation in the first place.

Fortunately, there are also ways to escape from combat situations that don’t undermine the narrative of the game. This post will discuss some of those techniques for GMs to end the combat without breaking the game’s immersion.

Negotiating a Cease Fire

Not every combat needs to continue until one side dies or passes out. One side may recognize that the other side wants something other than their death, and can offer to negotiate in exchange for safety. Or, the participants may be governed by a code of conduct (or legal norms) that accord privileges to those wishing to negotiate a stand-down.

Jack Sparrow invoking the right of parlay
Jack Sparrow invoking the right of parlay

In Pirates of the Carribbean, Jack Sparrow is captured at gunpoint when he remembers that the pirate code entitles him to parlay. He invokes his right to negotiate with the captain and is guaranteed safety until the negotiations are concluded. Jack is not out of the woods—and in fact his negotiations do not end well—but he averts his nearly certainty death at the hands of the crew.

The GM should make sure that his or her players know negotiated surrender is an option. But, the GM can also take the initiative in calling for negotiations. When the NPCs are firmly in control, negotiating for their goal is less risky than chancing a lucky shot from the PCs. As a result, the NPCs may have an incentive to de-escalate the situation and make the PCs bear the burden of their loss in the terms of surrender.

To set up a negotiated settlement, the GM should think through what motivates the NPCs. If the NPCs are simply cannon fodder for adventurers, then negotiation isn’t likely. However, if the NPCs have their own goals, pressures, and responsibilities, then there is room to negotiate a solution that moves the NPCs closer to their objectives.

Changing the Environment

Most new GMs think about the combat environment as a constant: once the space is set up, the characters make the action happen. But, the environment doesn’t have to be fixed. A power outage can cause the lights to go out, letting some characters escape, or the ledge suspended over a chasm can crack, threatening the safety of the characters standing there. Even something as simple as the passage of time can have an effect: when the sun rises, undead may have to retreat to the shadows.

If the PCs are truly overwhelmed, the GM can strategically change the environment to give them the initiative or provide a route for escape.

Changing the environment works best when the GM doesn’t save it for emergencies only. If the GM only changes the environment when the PCs are up against the wall, it feels like a cop-out. But, the GM can make environmental changes regular parts of the combat experience. Mist and smoke can obscure the battlefield as combat goes on; the walls can start to crack from the force of repeated impacts. Rivers can flood, fires can spread, reinforcements and allies can show up, and mana levels can ebb and flow. Having the environment change every round or two of combat makes battles feel more dynamic.

A savvy GM will mix up the impact of environmental changes. If the environment always benefits the players, it feels gimmicky. But if the changes sometimes benefit the opposition, they makes combat feel more uncertain and tense. Some environmental changes can be neutral, forcing both parties to adapt their tactics; others can be curve balls that change the whole dynamic of the encounter.

The GM can also gain credibility when changing the environment by linking environment changes to combat events. A boulder is unlikely to appear out of nowhere and cut off the pursuers—but if the characters were setting off explosives, suddenly the resulting avalanche is a creative effect of their actions.

Shifting the Threat

When one threat is poised to wipe out the party, the GM can breathe life into the encounter by shifting the threat to an even greater danger.

Fellowship of the Ring surrounded by goblins
Fellowship of the Ring surrounded by goblins

In The Fellowship of the Ring, the party seems doomed when they are surrounded by goblins deep in the mines of Moria. But, when the goblins hear a noise from the depths, they run away in a blind panic and leave the party to their own devices. Why? Because it turns out that goblins are not the worst thing in the dungeon—not by a long shot. The dungeon is also inhabited by a Balrog, a demon that so outclasses the goblins that they will flee for their lives even in the face of overwhelming victory against the party. With the goblins dispersing, Gandalf is free to lead the group on a wild race to escape the Balrog and find safety.

This trope of shifting the threat occurs in many works. For instance, in Jurassic Park, the protagonists are trapped by velociraptors in the Visitor Center, and they seem doomed until a T-rex breaks in and takes out the raptors. A variation of this trick occurs in Star Wars IV: A New Hope; the Tuscan Raiders that have captured Luke are scared away by the sound of a desert creature (that turns out to be a ruse played by Obi-Wan Kenobi).

Shifting the threat is a little bit of a deus ex machinca, so it needs to be used with care. It works best when the now-vulnerable antagonists have reason to think that the new threat is more dangerous, and it keeps the tension high if the PCs face greater risk as well. Note that the risk doesn’t have to be the same: the Balrog is threatening as a magical creature, while the goblins simply posed a mundane threat. What matters is that the stakes feel raised.

A little bit of foreshadowing can also improve how shifting the threat is received. The tyrannosaur is set up as a dangerous predatory early in Jurassic Park, so the T-rex’s attack doesn’t come out of nowhere.

To prepare the game for a possible shift in threat, the GM can think about who or what else is involved in the game world. Are there mutual opponents that can intrude? Do the antagonists have their own rivals that may interfere? Setting up these kinds of interconnected plot lines also makes the world feel three-dimensional, which enhances the atmosphere of the game.

Playing into Overconfidence

Finally, the antagonists do not need to go for the killing blow right away. Villains are frequently victims of their own hubris. They stop to gloat, to share their plans for inevitable victory, and to force the protagonists to watch their triumph.

If it fits with the personality of the NPCs, this option can be used to end a combat scene without a TPK. The player characters can be surrounded and lectured by the antagonist, who accidentally reveals a secret that the PCs can exploit. Or, the PCs may simply have enough time to catch their breath, recover a fatigue point, and overwhelm the opposition with a surprise all-out blitz.

Antagonists will frequently choose to capture the main characters and lock them away rather than killing them outright. GMs can easily use that option in order to end the combat and steer the campaign into a jail break scene. Depending on the genre of the game, it may be appropriate to include an interrogation session or an attempt to torture the PCs for further information; in other genres, the PCs may discover additional captives that can be allies in their escape attempt. Sometimes, the PCs may be able to bribe a guard to help them sneak away; other times, the captors are simply inattentive or overlook crucial details. Any of these options creates interesting possibilities for the game to advance.

Summary: Keep the Story Going

These four techniques to abort a combat scene all give GMs the ability to adjust on the fly if an encounter is too challenging for the PCs. The important thing is that all of these methods keep the story going. By adding twists to the situation, the GM can make the story more compelling. Having these techniques in your back pocket is a far better solution than simply fudging die rolls.

Understanding Reaction Modifiers

Reaction rolls are an easy way to add variety to NPC interactions. This post will flesh out what modifiers to reaction rolls mean in practice, so players and GMs can anticipate the impact of skills, appearance modifiers, and other game elements that influence reaction rolls.

Reaction Rolls in Brief

Whenever the characters encounter an NPC, the GM can choose to make a reaction roll in order to determine how the NPC responds to the player characters. Rolling a reaction simply means rolling 3d6, applying any modifiers, and comparing the result to the reaction table (on pp. B560–561).

Unlike success rolls, higher numbers are better for reaction rolls: an 18 means that the NPC is very favorably disposed to the PCs, while a 3 is an extremely bad reaction. The other major difference between success rolls and reaction rolls is that success rolls have a target number, while the results of reaction rolls fall on a spectrum. The worst response is a Disastrous reaction, and the reaction possibilities go up to Very Bad, Bad, Poor, Neutral, Good, Very Good, and Excellent.

Interpreting Reaction Modifiers

So, what does a +1 reaction modifier mean in practice? How badly is the party in trouble if they get a -2 reaction penalty? This post will translate the modifiers into game results below. All the odds are rounded for simplicity.

First, let’s establish the baseline. In an unmodified reaction roll, the players have a better than 6-in-10 chance of getting a Neutral or better reaction, with a 25% total chance of getting a Good or Very Good reaction. The absolute extremes—Disastrous for a bad reaction, or Excellent for a good reaction—are impossible on an unmodified roll. In short, a neutral reaction means that PCs will generally be given a fair hearing.

Odds for unmodified reaction roll results
The red line shows the odds for rolling a given reaction or better

Reaction Bonuses

With a net +1 reaction bonus, the PCs have an almost 75% chance of getting a Neutral or better reaction, and over 1/3 of the time, they will get a positive reaction. On the extremes, it is impossible to get either a Disastrous or Very Bad reaction, and there is a slight chance (0.5%) of getting an Excellent reaction. A little social influence goes a long way to smoothing edges, so negative reactions are exceptions rather than the rule.

Reaction Roll Results (+1 Bonus)

A net +2 bonus shifts expectations even further. Over half of the time, the PCs will get a Good reaction; Neutral is now below expectations! The odds of getting a Bad or Poor reaction are only 16%. In other words, it is unusual for NPCs to dislike the PCs when they have a net +2 bonus.

Reaction Roll Results (+2 Bonus)

If the PCs can earn a +4 reaction bonus (which is attainable by a combination of appropriate skill use, appearance or reputation modifiers, and/or situational modifiers), they will get a Good or better reaction three times out of four. In addition, they have an almost 10% chance of getting an Excellent reaction, zero chance of a Bad or worse reaction, and less than 5% chance of getting any reaction below Neutral. It’s really hard to hate someone with a +4 bonus!

Reaction Roll Results (+4 Bonus)

Above +5 net bonus, and we’re getting into saving-babies-from-burning-buildings territory: the median reaction is Very Good, the PCs have double-digit percent chances of Excellent reactions, and it requires the equivalent of a critical failure to get a less-than-Neutral reaction (and by +7, even the worst dice can’t cause a negative reaction).

Reaction Penalties

On the negative side, a net -1 reaction penalty is tolerable: the average roll will still be a Neutral or better reaction, and there is no chance of either extreme (Disastrous or Excellent). However, the odds of getting any positive reaction have fallen by about 10%, while the chances of getting a Bad or Very Bad reaction have nearly doubled (from 9% to 16%). Another way to look at the -1 penalty is to say that you have 50% odds of a negative reaction vs. a 50% chance of a Neutral-or-better reaction. Neutral is now a good outcome.

Reaction Roll Results (-1 Penalty)

With a net -2 penalty, the expected result shifts down to a Poor reaction, and the PCs will have a below-Neutral result almost 2/3 of the time. There’s still no chance of a Disastrous reaction, but the odds of a Very Good reaction have fallen to 0.5%. With this level of distaste, the PCs are consistently getting started on the wrong foot and having to recover from their social missteps.

Reaction Roll Results (-2 Penalty)

At a -3 penalty, Disastrous reactions become possible, while the odds of a Good reaction fall below 5%. There’s still a 1-in-3 chance of a Neutral reaction, but that’s definitely an above-average outcome. When the penalties get up to -4, the PCs have an equal chance of getting a Disastrous reaction as they have for getting any kind of positive reaction!

Reaction Roll Results (-4 Penalty)

Once the penalties combine for a -5 modifier, the PCs should probably hide their faces and prepare to be ambushed: they will experience a Bad reaction almost 2/3 of the time. Even a Neutral reaction will occur less than 10% of the time; this is the level where people are no longer willing to let bygones be bygones.


Ballparking Fatigue Costs

Fatigue is the odd stat out in GURPS. The basic attributes are relatively straightforward, and  most players and GMs grasp the purpose of hit points. Fatigue can easily become a throwaway stat, used only to fuel exotic abilities like powers or magic or to give the character a little extra oomph in combat. That’s unfortunate. Fatigue is an easy way to challenge characters by making their decisions take a toll, without requiring anything beyond the GURPS Lite rules. This post will present a rules-light way to ballpark fatigue costs so GMs can incorporate fatigue into their campaigns.

Fatigue Basics

Fatigue rules in Basic Set
Fatigue rules in Basic Set

As a quick recap: every GURPS character has a maximum number of fatigue points (FP), which defaults to their HT level. Characters can spend FP to do physical tasks, to use extra effort in a situation, or to cast spells; some special abilities also require FP in order to function. Just like hit points, spending FP comes at a cost: when a character is below 1/3 of their maximum FP, they move slower and can carry less. When characters go below 0 FP, they start to take damage from additional FP loss and are at risk for collapsing from exhaustion. Fatigue points can be recovered in a variety of ways, most commonly by resting.

Fatigue is a natural fit for gritty or realistic campaigns; in fact, the After the End series expands the fatigue rules to convey the grim reality of survival in a post-apocalyptic world. But it can also be used to great effect in cinematic campaigns, superhero dramas, or action adventures by showing how the characters need to push themselves to the limit in order to best the challenges they face.

The rules for fatigue are detail-driven, both in the Basic Set‘s presentation as well as the more abbreviated listing in GURPS Lite. Sometimes you can roll against a skill to avoid spending fatigue points (FP). Other times, you have to spend FP when doing an action regardless of how skilled the character is. Sometimes fatigue costs are modified based on the PC’s encumbrance; other times they are not. The intervals for spending FP vary in unpredictable ways: it costs 1 FP to dig in loose soil for an hour, but 1 FP per minute for paced running (unless you succeed at a Running or HT roll).

Rough Fatigue Costs

This post aims to make it easier for GMs to include fatigue in their games by helping them ballpark fatigue costs. Instead of being rules-dependent and spending time looking up exactly how many FP it costs to hold your breath underwater for a minute, GMs can use their judgment to impose fatigue costs on the PCs and keep the game rolling.

Strenuous Effort: 1 FP

When a PC performs a physically demanding task, that task usually costs 1 FP. The examples below are all represented as 1 FP cost activities:

  • Fighting a battle
  • Hiking
  • Swimming
  • Digging
  • Missing a meal
  • Becoming dehydrated
  • Not getting enough sleep (staying up too long or waking up early)
  • Exposure to extreme temperatures
  • Using extra effort in combat
  • Using extra effort for a physical task that exceeds your normal limits
  • Casting a known Sorcery spell
  • Casting simple magic spells like Awaken, Deflect Energy, Light, or Minor Healing

There is a lot of variety within this category, which is good for the rules light approach because it makes 1 FP cost a fair default. Again, the rules vary on many of the details, such as how often someone must pay the fatigue cost or whether the player can roll against a skill in order to avoid the fatigue cost.

It’s helpful to remember the context: the default human has 10 FP, so the standard is that someone could do these things 10 times without rest before being at risk of passing out due to exhaustion. That baseline can help the GM estimate the frequency for these costs; you might impose the cold exposure cost every minute for being in cold water, but only once per hour for being underdressed in cool weather.

If your game assumes that players have skills for lots of physical tasks, like Running, Swimming, or Survival, then it makes sense to allow the players to roll in order to avoid spending fatigue. But, that’s a play style choice, and there’s nothing wrong with a game that decides to ignore those skills and just charge the FP, or to have the players roll against HT instead of the specific skill.

Especially in a rules-light game, it’s important to remember that managing player expectations is more important than being precise according to the laws of physics. As long as players know that cold exposure is exhausting their characters and they have time to react to that information before the PCs keel over, the exact rate for imposing fatigue costs is not critical. Roll if it’s appropriate, charge the first FP, tell the players how long they have before they will lose the next FP, and let the players decide how to respond.

Encumbrance: 1 FP per level

Many of the physical tasks that cost fatigue points also have a leveled effect based on how encumbered the PC is. For each level of encumbrance, the character needs to spend an additional FP beyond what is normally required for the task. For instance, a character fighting a battle with medium (level 2) encumbrance would pay 1 FP for the battle and an additional 2 FP for being encumbered, for a total of 3 FP.

The GM should charge the encumbrance penalty when it makes sense. Running, swimming, and lifting heavy objects are situations in which encumbrance would logically make the task more exhausting. By contrast, holding your breath underwater, missing a meal, or being exposed to extreme temperatures are probably not affected by encumbrance levels.

Draining Effort: 2 or More FP

Compared to the variety of conditions that cost a single fatigue point, there aren’t many canonical examples of actions that cost multiple fatigue points in a single act. High acceleration, thermal shock, poison, and the drop-off effect from stimulants can all cost multiple FP at once. These examples all represent situations that genuinely drain the PC; they need to be cautious about additional exposure in order to avoid damage and unconsciousness.

The major source of multiple FP actions is magic. In the Basic Set magic system, about 50 of the spells fall into this range. In Sorcery, improvised magic or casting known spells at higher levels requires multiple FP. Ritual Path Magic quirks can include fatigue costs, averaging just under 2 FP for a single quirk up to almost 6 FP for a triple quirk.

In general, acts that require multiple fatigue points per use are explicitly intended to be limiting. If a character has to pay that cost multiple times, they will quickly run into the 1/3 FP threshold that imposes severe restrictions on the character’s abilities. As a result, GMs should save multi-FP costs for situations that are intended to make an unmistakable impact.

All-Out Effort: 5 FP and Higher

Once a character is paying 5 FP for a single situation, there’s very little room for error. Almost any additional fatigue costs would push an average character below the 1/3 threshold, and attempting the all-out stress a second time would put the character at risk of passing out.

The only mundane situations that would cost that much fatigue are engaging in strenuous effort while encumbered at the highest level (extra-heavy) or failing a roll for an extreme situation like thermal shock by a massive margin.

For a character to spend 5 FP or more at a time, the player really needs to plan ahead. The character probably need to invest in additional FP (or energy reserves, for mages). Otherwise, the character needs a way to gather or recover that energy: the Fit advantage, power stones, high skill levels to gather ambient energy, or the like. It’s simply not sustainable for characters to spend that much effort without advance planning.

As a result, the GM and players should plan together for any situations that might require all-out effort levels of fatigue. Magic users or characters with superpowers that require high fatigue expenditures should recognize those choices during the character creation process, so they should be equipped to handle those situations. Likewise, if the GM anticipates an all-out fatigue expenditure event as part of the campaign arc (e.g., if the characters will need to survive on an ice planet), then the players should be prepared for that during character creation as well so they can build their characters appropriately.

Fatigue the Rules Light Way

Using these guidelines, it’s relatively easy to assign reasonable FP costs in-game:

  • Most cases of extraordinary physical exertion, challenging environmental conditions, or invoking powers cost 1 FP
  • When performing physically taxing tasks, encumbrance costs additional FP per level of encumbrance
  • Acts or conditions that cost multiple FP should represent intentionally severe situations
  • The GM should be very cautious about assigning a fatigue cost above 2 FP
  • If fatigue costs above 5 FP are possible, the players should know in advance so they can make sure their characters are equipped to handle the challenge

Keeping Decisions Interesting

One of the things that distinguishes GURPS from other RPGs is that GURPS allows gamers to play with a variety of degrees of granularity. It is possible to run a game that requires players to track lots of details, but it is equally possible to run a game that focuses on a couple of core skills with generic difficulty modifiers. The key to making GURPS accessible is remembering to limit the decision-making so that all the decisions are interesting.

The Granularity Spectrum

To visualize this idea, imagine a spectrum of granularity. At one extreme of the spectrum, there are almost no details to track: the characters have the four basic attributes, a handful of skills, and the game exclusively uses generic task difficulty modifiers. This end of the spectrum doesn’t require many decisions: character creation is straightforward, there aren’t a ton of mechanical options to consider in play, and most of those mechanical decisions will be blunt choices along the lines of “I choose to attack” or “I choose to run away.”

At the other end of the spectrum, play can revolve around a myriad of complicating factors: choosing between skills with shades of differences (like Physician vs Diagnosis) after factoring in situational modifiers, defaults, talents, and the like. At this level, players can be required to make decisions about how to manage the number of bullets they are carrying, their exact positioning on a tactical grid, etc.

Neither extreme is necessarily right or wrong. The key factor is whether the decisions are interesting. In other words, are there compelling consequences to the decisions so that the players are invested in what they decide?

The extreme granularity may be too overwhelming for a new player who doesn’t understand enough about the options to make intelligent choices about the options available. Having to make all those decisions isn’t interesting—it’s burdensome. The significance of the options is lost if the players are struggling to keep up with the available options.

Conversely, the less detailed extreme may gloss over too many decisions for a more experienced gamer, leading to boredom and a lack of strategic choices. The game may be less fun because there aren’t enough decisions to keep the players engaged, and the decisions that are available are at too high a level of abstraction to be meaningful.

Choosing Your Game’s Granularity

When deciding how to run a game, the GM and players should decide what level of granularity they want in order to encourage interesting decisions without being overwhelming. If the players are less experienced or have less knowledge of the system, they may not be able to take advantage of the decisions available under more granular options. If the gamers want to run a lighter game, rules-heavy options will be cumbersome. If the participants enjoy detailed resource management, more granular games may offer them opportunities to make more interesting choices.

Remember that granularity is not all-or-nothing. In fact, one of the things GURPS does really well is creating a self-consistent gaming system. You can easily choose to use very detailed rules for one element of the game and use less detailed rules for other elements. If you want to have tons of combat detail but treat social interactions as a generic Persuasion skill, you can. If you want to get into tons of detail for planning and strategizing how to pull off a heist, but leave the details of getting the job vague, it’s doable. Almost any subsystem of the game—powers, magic, social interaction, combat, starting the adventure, travel, healing, after-encounter cleanup—can be treated with extreme detail, or simplified with a single dice roll or even narrated without dice.

Adjust Granularity on the Fly

Because GURPS is a consistent system, you can adjust the granularity on the fly. If your players are overwhelmed by the number of decisions they need to make, simplify things! Use skill checks with task difficulty modifiers rather than digging into techniques or situational modifiers, stop tracking encumbrance or fatigue, and restrict the combat options available.

Conversely, when your players start to feel that the game is too simplistic, turn up the granularity so they have to face more tradeoffs. Introduce penalties for specific techniques, lack of familiarity, or equipment quality; track their encumbrance and require fatigue points for pushing their limits. Expand the combat rules in play and start having the NPCs make smart tactical decisions so your players need to up their tactical game.

By starting simple and gradually adding in granularity in order to keep the players engaged, you can keep the game accessible and fun. When the decisions are interesting, so is the game!


Simplify the Game with GM Style, Not Rules

An easy way to simplify GURPS is to adjust the GM style to fit the kind of game that your group wants to play. Many groups assume that, because GURPS has rules for a wide variety of situations, they need to use those rules in order to model their game. Not true! GURPS is great for less complex games and less-rules-intensive play. The GM just needs to set the right expectations.

Toolkits Can Simplify

GURPS is often described as an RPG toolkit: it contains all the tools you need to run any kind of game you can imagine. All you have to do is pull the right tools out of the box by choosing the right rules, genre restrictions, etc.

The toolkit metaphor is accurate but misleading because it emphasizes all the tools available. As a result, too many people have the impression that GURPS is rules heavy; they see the full toolkit and assume that that’s what they have to play with. But, an important part of a tool kit is that it holds a bunch of tools that you don’t need for the project in question. When you’re actually doing construction, you pull out a couple of tools and you work with those tools. You don’t work with the whole toolkit at once. And, as long as your chosen tools are doing what you need, you can ignore everything else in the toolkit. You only need to open up the toolkit again when you realize that you need another tool that you haven’t yet pulled out.

One of the ways that the GURPS toolkit enables gamers to simplify is by turning rules off. The Introduction to the Basic Set is clear that the participants can choose what rules to use:

“The rulebooks include a lot of detail, but…all that detail is optional – use it only when it makes the game more fun” (p. B8).

The GURPS combat system—a part of the game that can seem rules-dense—is explicitly described as a part of the game that can be turned on and off. Again from Basic Set:

“But the combat system is ‘modular’; you can use all the rules for a complex, detailed, realistic combat simulation – or just those in Chapter 11 for a quick game” (p. B9).

Rules or GM Style?

Because GURPS has rules to cover such a variety of situations, it’s possible to find a rule that creates the effect you want. But, that doesn’t mean that’s the only way to create that effect. You can also create effects by changing the way that the gamemaster runs the game.

Let’s take a concrete example. Let’s say that you want to run a hack-and-slash campaign, and you’re worried about the rules for shock penalties slowing down the excitement. You have options for how to create that effect.

The first option that most people will think about is looking for rules to counteract shock penalties. In this case, there’s an advantage that has that effect: High Pain Threshold. By having all the PCs buy High Pain Threshold (and with the GM giving that advantage to all the relevant NPCs), that rule is turned off.

But, what if you’re not fluent in GURPS and don’t know which advantage has that effect? What if you’re not certain that there is such an advantage? Or what if you are running a game for new players that are trying to learn success rolls and DR, and aren’t yet ready to grapple with High Pain Threshold? That’s where option 2 comes in: just change your GM style.

The GM can decide that, for this campaign, shock penalties don’t fit into the game. As a result, the GM can simply handwave away shock penalties: no advantage needed, no rules lookups to determine what the advantage is or what other consequences it has. There’s nothing wrong with this method of play! As long as the GM is clear with the players so that everyone has the same expectations, there’s no problem.

Ideas for GM Style Modifications

Almost any part of GURPS can be simplified through GM style rather than rules. Here’s a short list to get you started:

  • Combat can be streamlined by eliminating shock, wounding modifiers, postures, and hit locations.
  • Fatigue can be turned off, or only assessed at the GM’s discretion.
  • Encumbrance can be ignored or tracked for only major items to simplify bookkeeping.
  • Magic can be simplified by substituting GM judgment for prerequisite lists.

If you want to simplify the game, go for it! Just make sure that the GM communicates with the players so everyone is on the same page. If for some reason the simplified gameplay ends up broken, you can always revisit the decisions with the group to create a game that everyone enjoys.