Players and GMs that are new to GURPS often feel overwhelmed by the sheer number of details that can be gamed. Take shooting a gun: how long did you aim? How far away is your target? Is your target moving? Is your target under cover? Is your vision obscured by cover? How many bullets are you firing? Trying to put all these details together on-the-fly is not easy.
The key to remember is that all of these rules are optional. From the Introduction to the Basic Set (Fourth Edition):
“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).
If keeping track of dozens of modifiers doesn’t sound like fun, don’t do it! GURPS is flexible enough to give you a great game without requiring you to use a spreadsheet.
The Solution: Task Difficulty Modifiers
The point of all those modifiers is to refine the success roll mechanic. In general, success rolls are made against a character’s skill level. The modifiers are used because some tasks are unusually difficult (or easy), and the character’s chances of success should reflect that difficulty. So, if you don’t want to figure out those modifiers, what do you do?
The Basic Set has a great tool for simplifying the game: task difficulty modifiers. Instead of adding up all the various elements of the task that make it easier or harder than normal and generating a net modifier, task difficulty modifiers let the GM assign a single modifier to the whole task. A normal adventuring task gets a +0 modifier—the roll is unchanged. Slightly harder tasks can be modified with a -1 or -2; moderately difficult situations can be given a -4, and so on until you are describing an all-but-impossible task by using a -10 modifier. The same principle works for easier-than-average tasks, with slightly easier tasks starting at +1 and trivially easy tasks getting a +10 bonus. The full chart, along with examples, is on pp. B345-346.
Unfortunately, the Basic Set doesn’t showcase task difficulty modifiers as well as it should. They are presented as the first of many kinds of modifiers that can be assessed to a success roll—along with equipment modifiers, time modifiers, cultural modifiers, and more. The key line that enables task difficulty modifiers to simplify GURPS is buried at the end of the section:
“The GM can use difficulty modifiers in place of other modifiers if the outcome of a task is too unimportant—or the action too hot—to justify stopping to add up a long string of modifiers” (B346).
That’s right—Rules As Written allow you to replace all the other modifiers with task difficulty modifiers. In my opinion, this line should have been front and center. Any time you want to dive into the details, GURPS is there with all the rules you could possibly need. But, every one of those detailed rules is optional. If your GM eyeballs a task difficulty modifier for every success roll, you’ll be in the same ballpark, and that’s all you need to make the gameplay plausible.
A Worked Example: Task Difficulty For A Secret Agent
Agent Vanessa Sadao is an undercover Infinity cop attempting to infiltrate a Centrum research lab on an alternate earth circa 1990. For this example, her key skills are Observation-12, Lockpicking-11, Fast-Draw-12, and Guns (Pistol)-13.
Beginning across the street from the lab, Agent Sadao looks over the facility to see if there are any guards. The GM decides that this is a slightly easier than normal task—although Sadao is on the opposite side of the street, the building is in the open, there is bright daylight, and the lab building doesn’t have any obvious concealments. The GM assigns this task a net +2 modifier and rolls in secret against Sadao’s effective Observation of 14, telling Sadao’s player that the coast appears clear.
Let’s compare that estimate to a more detailed treatment of the rules. Vision rules are described on p. B358. Assume that there aren’t any guards that are trying to hide; this building simply has a normal patrol of guards. In that case, there are two relevant modifiers—size and range from the target and potentially the bonus for looking for something in plain sight. Depending on how big the street is, the range penalty could be anything from -6 (for 20 yards) to -10 (for 100 yards). On the other hand, the bonus for looking for something in plain sight is +10. So, the calculated modifier would be between +0 and +4. The estimated task difficulty is pretty close!
Thinking that the coast is clear, Sadao approaches the door and attempts to pick the lock. The GM rules that this task gets a -4 modifier because it’s more difficult than usual; Sadao has a basic lockpicking set, but Centrum has a well-designed lock. She rolls against her effective Lockpicking skill of 7 and fails; the GM rules that she opens the door but set off the alarm while doing so.
Based on that description, the detailed treatment revolves around equipment modifiers. On p. B345, basic equipment gets no modifier. Fine equipment (like Centrum’s locking mechanism) gets a +2 bonus; since that’s what Sadao is working against, we’ll treat that bonus as a penalty to this roll. (If Centrum had the best equipment possible at this tech level, the equipment modifier on Centrum’s side would be +4.) So, a calculated modifier would come out to -2 or -4, depending on how good Centrum’s lock really is. Again, the estimate is close.
Hearing the alarm, Sadao—and the guard on the other side of the door that she’s about to meet—immediately prepare for the worst. They are both surprised, so the GM rules that they act in normal order, with Sadao going first because she has a higher Basic Speed.
She tries to ready her gun immediately with Fast-Draw. The GM rules that there’s no modifier for this attempt—this is exactly what Fast-Draw is supposed to cover. She rolls against her unmodified Fast-Draw skill and succeeds, so she can take an Attack maneuver during her first turn. She decides to take a normal attack because she is worried about other guards showing up and doesn’t want to sacrifice her ability to dodge. Because the guard is only a couple of yards away, the GM estimates the task difficulty at +0—a standard adventuring task—and Sadao succeeds by rolling under her effective skill of 13. The guard misses his Dodge attempt, and as he slumps to the floor Sadao takes a moment to reassess her break-in attempt.
In detailed terms, the GM could choose to assign a penalty for a minor distraction (the alarms), which would be -2. There’s no range penalty unless the guard is at more than two yards away, and even at 5 yards the penalty is only -2. So, a net modifier of 0 is plausible, -2 is fair, and -4 is possible if the GM gives no quarter to Sadao’s player.
In all of these cases, estimated task difficulties came out pretty close to a calculated modifier. And, more importantly, the task difficulty modifiers all make sense in the context of the game. Based on what the players described, no one is going to say that the assigned modifier is unrealistic. No GM is going to say that checking the building for guards is a -6 difficulty, or that picking the lock deserves a +4 bonus. As long as the modifier produces a playable result, it’s done its job.
If your goal is to play a simple game, then task difficulty modifiers are a great tool for cutting through the details and making GURPS into a straightforward and uncomplicated system.