The following posts will describe how the game system works. I will be pulling and paraphrasing entries directly from the free Gurps Lite manual available to everyone. A link for one can be found in the Gurps Resources sub thread.
A more in-depth section on combat and maneuvers will be described in a separate thread named Combat. For now, we will go over the dice rolling mechanics of the game down below and some of its application.
How the Gurps System works
Re: Character Creation basics for GURPS
When to roll
GURPS uses six-sided dice only, this helps keep our dice rolling macros simple. Whenever a character attempts to perform an action (e.g., use a skill), roll three dice to determine the outcome. This is called a success roll. The task in question succeeds if the total rolled on the dice is less than or equal to the number that governs the action – most often a skill or an attribute. Otherwise, it fails. For example, if you are rolling against Strength, and your ST is 12, a roll of 12 or less succeeds. Thus, the higher the stat you are rolling against, the easier it is to make the roll. Regardless of the score you are rolling against, a roll of 3 or 4 is always a success, while a roll of 17 or 18 is always a failure.
To avoid bogging down the game in endless die rolls, especially for some of the crunchier aspects of GURPS, players in this game will only need to roll the dice if a character’s health, wealth, friends, reputation, or equipment are at risk. This includes chases, combat (even if the target is stationary and at point-blank range!), espionage, thievery, and similar “adventuring” activities. Success rolls will also be asked for if the character stands to gain allies, information, new abilities, social standing, or wealth.
GURPS uses six-sided dice only, this helps keep our dice rolling macros simple. Whenever a character attempts to perform an action (e.g., use a skill), roll three dice to determine the outcome. This is called a success roll. The task in question succeeds if the total rolled on the dice is less than or equal to the number that governs the action – most often a skill or an attribute. Otherwise, it fails. For example, if you are rolling against Strength, and your ST is 12, a roll of 12 or less succeeds. Thus, the higher the stat you are rolling against, the easier it is to make the roll. Regardless of the score you are rolling against, a roll of 3 or 4 is always a success, while a roll of 17 or 18 is always a failure.
To avoid bogging down the game in endless die rolls, especially for some of the crunchier aspects of GURPS, players in this game will only need to roll the dice if a character’s health, wealth, friends, reputation, or equipment are at risk. This includes chases, combat (even if the target is stationary and at point-blank range!), espionage, thievery, and similar “adventuring” activities. Success rolls will also be asked for if the character stands to gain allies, information, new abilities, social standing, or wealth.
Re: Character Creation basics for GURPS
Modifiers
The rules often specify modifiers for certain success rolls. These bonuses and penalties affect the number you are rolling against – your “target number” – and not the total rolled on the dice. Bonuses always improve your odds, while penalties always reduce them.
For instance, when using the Lockpicking skill in the dark, the GM might tell you to roll at -5 for the attempt. If your Lockpicking skill is 9, you roll against 9 minus 5, or 4, in the dark. A specific scenario might provide modifiers to allow for the relative ease or difficulty of a particular situation. For instance, an adventure might state that a lock is +10 to open due to the fact that it is primitive and clumsy. If your Lockpicking skill were 9, you would roll against 9 + 10, or 19. Since the highest roll possible on 3d is 18, it would seem that success is assured. Not quite – see Critical Success and Failure, below.
Modifiers are cumulative unless stated otherwise. For instance, if you tried to open that primitive lock in the dark, both modifiers would apply, and you would roll against 9 - 5 + 10, or 14. Base Skill vs. Effective Skill Your base skill is your actual level in a skill, as recorded on your character sheet. Your effective skill for a particular task is your base skill plus or minus any modifiers for that task. In the Lockpicking examples above, the base skill is 9 in all cases, while the effective skill is 4, 19, or 14.
The rules often specify modifiers for certain success rolls. These bonuses and penalties affect the number you are rolling against – your “target number” – and not the total rolled on the dice. Bonuses always improve your odds, while penalties always reduce them.
For instance, when using the Lockpicking skill in the dark, the GM might tell you to roll at -5 for the attempt. If your Lockpicking skill is 9, you roll against 9 minus 5, or 4, in the dark. A specific scenario might provide modifiers to allow for the relative ease or difficulty of a particular situation. For instance, an adventure might state that a lock is +10 to open due to the fact that it is primitive and clumsy. If your Lockpicking skill were 9, you would roll against 9 + 10, or 19. Since the highest roll possible on 3d is 18, it would seem that success is assured. Not quite – see Critical Success and Failure, below.
Modifiers are cumulative unless stated otherwise. For instance, if you tried to open that primitive lock in the dark, both modifiers would apply, and you would roll against 9 - 5 + 10, or 14. Base Skill vs. Effective Skill Your base skill is your actual level in a skill, as recorded on your character sheet. Your effective skill for a particular task is your base skill plus or minus any modifiers for that task. In the Lockpicking examples above, the base skill is 9 in all cases, while the effective skill is 4, 19, or 14.
Re: Character Creation basics for GURPS
Degree of Success or Failure
Once you have calculated your effective skill by applying all the relevant modifiers to your base skill, roll 3d to determine the outcome. If the total rolled on the dice is less than or equal to your effective skill, you succeed, and the difference between your effective skill and your die roll is your margin of success.
Example: If you have effective skill 18 and roll a 12, you succeed; your margin of success is 6. If you roll higher than your effective skill, you fail, and the difference between the die roll and your effective skill is your margin of failure.
Example: If you have effective skill 9 and roll a 12, you fail; your margin of failure is 3.
Many rules use margin of success or failure to calculate results that matter in play, so be sure to note it when you roll.
Critical Success and Failure
A critical success is an especially good result.
• A roll of 3 or 4 is always a critical success.
• A roll of 5 is a critical success if your effective skill is 15+.
• A roll of 6 is a critical success if your effective skill is 16+.
When you roll a critical success, the GM determines what happens. It is always something good! The lower the roll, the better “bonus” he gives you.
A critical failure is an especially bad result.
• A roll of 18 is always a critical failure.
• A roll of 17 is a critical failure if your effective skill is 15 or less; otherwise, it is an ordinary failure.
• Any roll of 10 or more greater than your effective skill is a critical failure: 16 on a skill of 6, 15 on a skill of 5, and so on.
When you roll a critical failure, the GM determines what happens. It is always something bad – the higher the roll, the worse the result.
Once you have calculated your effective skill by applying all the relevant modifiers to your base skill, roll 3d to determine the outcome. If the total rolled on the dice is less than or equal to your effective skill, you succeed, and the difference between your effective skill and your die roll is your margin of success.
Example: If you have effective skill 18 and roll a 12, you succeed; your margin of success is 6. If you roll higher than your effective skill, you fail, and the difference between the die roll and your effective skill is your margin of failure.
Example: If you have effective skill 9 and roll a 12, you fail; your margin of failure is 3.
Many rules use margin of success or failure to calculate results that matter in play, so be sure to note it when you roll.
Critical Success and Failure
A critical success is an especially good result.
• A roll of 3 or 4 is always a critical success.
• A roll of 5 is a critical success if your effective skill is 15+.
• A roll of 6 is a critical success if your effective skill is 16+.
When you roll a critical success, the GM determines what happens. It is always something good! The lower the roll, the better “bonus” he gives you.
A critical failure is an especially bad result.
• A roll of 18 is always a critical failure.
• A roll of 17 is a critical failure if your effective skill is 15 or less; otherwise, it is an ordinary failure.
• Any roll of 10 or more greater than your effective skill is a critical failure: 16 on a skill of 6, 15 on a skill of 5, and so on.
When you roll a critical failure, the GM determines what happens. It is always something bad – the higher the roll, the worse the result.
Re: Character Creation basics for GURPS
Repeated Attempts
Sometimes you only get one chance to do something (defuse a bomb, jump over a crevasse, remove an inflamed appendix, please the King with a song). Other times you can try over and over again until you succeed (pick a lock, catch a fish, analyze a poison). Still other times you will not know whether you succeeded or failed until it’s too late to try again (translate an old treasure map, order in a French restaurant, build a ship). Finally, there are times when you are injured by failure but can afford to fail a few times (climb a wall, impress a savage tribesman).
The GM must use common sense to distinguish among these cases, according to the exact situation in which the adventurers find themselves.
Contests
Sometimes a situation arises in which two characters must compare attributes, skills, or other traits to settle a competition. The one with the highest score doesn’t always win ... but that’s the way to bet. A “Contest” is a quick way to handle such a competitive situation without playing it out in detail. In a Contest, each competitor attempts a success roll against the ability being tested – with all applicable modifiers – and then compares his result to his opponent’s. There are two different ways to make this comparison.
Quick Contest - A “Quick Contest” is a competition that is over in very little time – often in one second, perhaps even instantly. Examples include two enemies lunging for a gun or two knife throwers seeing who gets closer to the bull’s-eye. Each competitor attempts his success roll. If one succeeds and the other fails, the winner is obvious. If both succeed, the winner is the one with the largest margin of success; if both fail, the winner is the one with the smallest margin of failure. A tie means nobody won (in the examples above, both fighters grabbed the weapon at once, or the knives hit the same distance from the bull’s-eye).
Margin of Victory - The amount by which the winner beat the loser is often important – success by 5 vs. failure by 5 generally means more than success by 2 vs. success by 1! The winner’s “margin of victory” is the difference between his margin of success and the loser’s margin of success if both succeeded, the sum of his margin of success and the loser’s margin of failure if he succeeded and the loser failed, or the difference between the loser’s margin of failure and his margin of failure if both failed.
Regular Contest - A “Regular Contest” is a slow competition with much give and take – for instance, arm wrestling. Each character attempts his success roll. If one succeeds and the other fails, the winner is obvious. If both succeed or both fail, the competitors’ relative positions are unchanged and they roll again. Eventually, one character succeeds when the other fails. At this point, the one who made his roll is the winner. The length of game time each attempt takes depends on the activity, and is up to the GM. In a combat situation, each attempt takes one second . . . but in a library-research contest, with the fate of the world hanging on who finds a certain obscure reference first, each attempt could represent days of time.
When performing contests, I will always take into consideration a character's speed (initiative). If you are faster, then their is no contest in terms of speed, you succeed. If your speed is the same as the opponents, then a contest will occur, since it is happening simultaneously.
Sometimes you only get one chance to do something (defuse a bomb, jump over a crevasse, remove an inflamed appendix, please the King with a song). Other times you can try over and over again until you succeed (pick a lock, catch a fish, analyze a poison). Still other times you will not know whether you succeeded or failed until it’s too late to try again (translate an old treasure map, order in a French restaurant, build a ship). Finally, there are times when you are injured by failure but can afford to fail a few times (climb a wall, impress a savage tribesman).
The GM must use common sense to distinguish among these cases, according to the exact situation in which the adventurers find themselves.
Contests
Sometimes a situation arises in which two characters must compare attributes, skills, or other traits to settle a competition. The one with the highest score doesn’t always win ... but that’s the way to bet. A “Contest” is a quick way to handle such a competitive situation without playing it out in detail. In a Contest, each competitor attempts a success roll against the ability being tested – with all applicable modifiers – and then compares his result to his opponent’s. There are two different ways to make this comparison.
Quick Contest - A “Quick Contest” is a competition that is over in very little time – often in one second, perhaps even instantly. Examples include two enemies lunging for a gun or two knife throwers seeing who gets closer to the bull’s-eye. Each competitor attempts his success roll. If one succeeds and the other fails, the winner is obvious. If both succeed, the winner is the one with the largest margin of success; if both fail, the winner is the one with the smallest margin of failure. A tie means nobody won (in the examples above, both fighters grabbed the weapon at once, or the knives hit the same distance from the bull’s-eye).
Margin of Victory - The amount by which the winner beat the loser is often important – success by 5 vs. failure by 5 generally means more than success by 2 vs. success by 1! The winner’s “margin of victory” is the difference between his margin of success and the loser’s margin of success if both succeeded, the sum of his margin of success and the loser’s margin of failure if he succeeded and the loser failed, or the difference between the loser’s margin of failure and his margin of failure if both failed.
Regular Contest - A “Regular Contest” is a slow competition with much give and take – for instance, arm wrestling. Each character attempts his success roll. If one succeeds and the other fails, the winner is obvious. If both succeed or both fail, the competitors’ relative positions are unchanged and they roll again. Eventually, one character succeeds when the other fails. At this point, the one who made his roll is the winner. The length of game time each attempt takes depends on the activity, and is up to the GM. In a combat situation, each attempt takes one second . . . but in a library-research contest, with the fate of the world hanging on who finds a certain obscure reference first, each attempt could represent days of time.
When performing contests, I will always take into consideration a character's speed (initiative). If you are faster, then their is no contest in terms of speed, you succeed. If your speed is the same as the opponents, then a contest will occur, since it is happening simultaneously.
Re: Character Creation basics for GURPS
Reaction Rolls
When the PCs meet an NPC whose reaction to them is not predetermined (see below), the GM makes a “reaction roll” on 3d. The higher the roll, the better the reaction. The GM then plays the NPC according to the guidelines on the Reaction Table. A reaction roll is not a success roll. There are three important differences:
1. There is no “target number” to roll against.
2. A high roll is good, not bad.
3. Reaction modifiers apply directly to the die roll. A reaction bonus is any factor that makes NPCs friendlier, while a reaction penalty is something that biases NPCs against the PCs.
Some common reaction modifiers:
Personal appearance and behavior. This is especially true for the PC who does the talking! Above-average appearance gives a bonus, as do some advantages. Below-average appearance and many disadvantages give a penalty.
Racial or national biases. Elves don’t like dwarves, Frenchmen don’t care for Germans, and so on. These are usually penalties, and take the form of an Intolerance disadvantage on the part of the NPC.
Appropriate behavior by the players! Here’s a chance to reward good roleplaying. A good approach should be worth +1 or more! A wholly inappropriate approach that antagonizes the NPCs should give the party -1 or -2 on the reaction roll.
A lot of these rolls will be done by me in the background, so its more of a passive bonus or penalty system for players who pay attention to that sort of stuff when building or playing out their characters. Strictly optional.
When the PCs meet an NPC whose reaction to them is not predetermined (see below), the GM makes a “reaction roll” on 3d. The higher the roll, the better the reaction. The GM then plays the NPC according to the guidelines on the Reaction Table. A reaction roll is not a success roll. There are three important differences:
1. There is no “target number” to roll against.
2. A high roll is good, not bad.
3. Reaction modifiers apply directly to the die roll. A reaction bonus is any factor that makes NPCs friendlier, while a reaction penalty is something that biases NPCs against the PCs.
Some common reaction modifiers:
Personal appearance and behavior. This is especially true for the PC who does the talking! Above-average appearance gives a bonus, as do some advantages. Below-average appearance and many disadvantages give a penalty.
Racial or national biases. Elves don’t like dwarves, Frenchmen don’t care for Germans, and so on. These are usually penalties, and take the form of an Intolerance disadvantage on the part of the NPC.
Appropriate behavior by the players! Here’s a chance to reward good roleplaying. A good approach should be worth +1 or more! A wholly inappropriate approach that antagonizes the NPCs should give the party -1 or -2 on the reaction roll.
A lot of these rolls will be done by me in the background, so its more of a passive bonus or penalty system for players who pay attention to that sort of stuff when building or playing out their characters. Strictly optional.
Re: Character Creation basics for GURPS
Reaction Table
Roll 3 dice and apply any reaction modifiers.
0 or less: Disastrous. The NPC hates the characters and will act in their worst interest. Nothing is out of the question: assault, betrayal, public ridicule, or ignoring a life-or death plea are all possible.
1 to 3: Very Bad. The NPC dislikes the characters and will act against them if it’s convenient to do so: attacking, offering grossly unfair terms in a transaction, and so on.
4 to 6: Bad. The NPC cares nothing for the characters and will act against them (as above), if he can profit by doing so.
7 to 9: Poor. The NPC is unimpressed. He may make threats, demand a huge bribe before offering aid, or something similar.
10 to 12: Neutral. The NPC ignores the characters as much as possible. He is totally uninterested. Transactions will go smoothly and routinely, as long as protocol is observed.
13 to 15: Good. The NPC likes the characters and will be helpful within normal, everyday limits. Reasonable requests will be granted.
16 to 18: Very Good. The NPC thinks highly of the characters and will be quite helpful and friendly, freely offering aid and favorable terms in most things.
19 or better: Excellent. The NPC is extremely impressed by the characters, and will act in their best interests at all times, within the limits of his own ability – perhaps even risking his life, wealth, or reputation.
Again, a lot of these reaction rolls are passive and will be based on your actions as a PC and whatever bonuses or penalties you give your character during character creation. Most encounters will default at 10 to 12, and go from there when applying modifiers.
Roll 3 dice and apply any reaction modifiers.
0 or less: Disastrous. The NPC hates the characters and will act in their worst interest. Nothing is out of the question: assault, betrayal, public ridicule, or ignoring a life-or death plea are all possible.
1 to 3: Very Bad. The NPC dislikes the characters and will act against them if it’s convenient to do so: attacking, offering grossly unfair terms in a transaction, and so on.
4 to 6: Bad. The NPC cares nothing for the characters and will act against them (as above), if he can profit by doing so.
7 to 9: Poor. The NPC is unimpressed. He may make threats, demand a huge bribe before offering aid, or something similar.
10 to 12: Neutral. The NPC ignores the characters as much as possible. He is totally uninterested. Transactions will go smoothly and routinely, as long as protocol is observed.
13 to 15: Good. The NPC likes the characters and will be helpful within normal, everyday limits. Reasonable requests will be granted.
16 to 18: Very Good. The NPC thinks highly of the characters and will be quite helpful and friendly, freely offering aid and favorable terms in most things.
19 or better: Excellent. The NPC is extremely impressed by the characters, and will act in their best interests at all times, within the limits of his own ability – perhaps even risking his life, wealth, or reputation.
Again, a lot of these reaction rolls are passive and will be based on your actions as a PC and whatever bonuses or penalties you give your character during character creation. Most encounters will default at 10 to 12, and go from there when applying modifiers.
Re: How the Gurps System works
Influence Rolls
An “Influence roll” is a deliberate attempt to ensure a positive reaction from an NPC. A PC with an appropriate “Influence skill” can always elect to substitute an Influence roll for a regular reaction roll in suitable circumstances (GM’s decision).
Decide which Influence skill you are using: Diplomacy, Fast-Talk, Intimidation, Savoir-Faire, Sex Appeal, or Streetwise. Choose wisely!
The GM may allow other skills to work as Influence skills in certain situations (e.g., Law skill, when dealing with a judge). Then roll a Quick Contest: your Influence skill vs. the subject’s Will. If you win, you get a “Good” reaction from the NPC – “Very Good” if you used Sex Appeal. On any other outcome, the NPC resents your clumsy attempt at manipulation. This gives you a “Bad” reaction – “Very Bad” if you attempted intimidation. Exception: If you used Diplomacy, the GM will also make a regular reaction roll and
use the better of the two reactions. Thus, Diplomacy is relatively safe . . .
An “Influence roll” is a deliberate attempt to ensure a positive reaction from an NPC. A PC with an appropriate “Influence skill” can always elect to substitute an Influence roll for a regular reaction roll in suitable circumstances (GM’s decision).
Decide which Influence skill you are using: Diplomacy, Fast-Talk, Intimidation, Savoir-Faire, Sex Appeal, or Streetwise. Choose wisely!
The GM may allow other skills to work as Influence skills in certain situations (e.g., Law skill, when dealing with a judge). Then roll a Quick Contest: your Influence skill vs. the subject’s Will. If you win, you get a “Good” reaction from the NPC – “Very Good” if you used Sex Appeal. On any other outcome, the NPC resents your clumsy attempt at manipulation. This gives you a “Bad” reaction – “Very Bad” if you attempted intimidation. Exception: If you used Diplomacy, the GM will also make a regular reaction roll and
use the better of the two reactions. Thus, Diplomacy is relatively safe . . .
Re: How the Gurps System works
Will Rolls
When you are faced with a stressful situation or a distraction, the GM may require you to roll against your Will to stay focused. On a success, you may act normally. On a failure, you submit to the fear, give in to the pressure, are distracted from your task, etc.
Fright Checks
A Fright Check is a Will roll made to resist fear. Fright Checks can occur as often or as rarely as the GM wishes. In a horror campaign where ordinary people meet shockingly gruesome Things, Fright Checks might be very common! With only minor adaptation, the GM can use these rules for awe, confusion, etc. as well as fear.
As a general rule, “ordinary” frightening things do not require Fright Checks. Fright Checks are for events so unusual and terrifying that they might stun or even permanently scar someone.
A Fright Check is subject to any number of modifiers, including ones derived from appropriate advantages or disadvantages, and the circumstances surrounding the roll. A failed Fright Check results in the character being stunned for a number of seconds equal to the margin of your failure, plus 2d. On a critical failure, the victim faints, and cannot be revived for the margin of failure plus 1d minutes. Hope the thing that scared you isn’t hungry . . .
When you are faced with a stressful situation or a distraction, the GM may require you to roll against your Will to stay focused. On a success, you may act normally. On a failure, you submit to the fear, give in to the pressure, are distracted from your task, etc.
Fright Checks
A Fright Check is a Will roll made to resist fear. Fright Checks can occur as often or as rarely as the GM wishes. In a horror campaign where ordinary people meet shockingly gruesome Things, Fright Checks might be very common! With only minor adaptation, the GM can use these rules for awe, confusion, etc. as well as fear.
As a general rule, “ordinary” frightening things do not require Fright Checks. Fright Checks are for events so unusual and terrifying that they might stun or even permanently scar someone.
A Fright Check is subject to any number of modifiers, including ones derived from appropriate advantages or disadvantages, and the circumstances surrounding the roll. A failed Fright Check results in the character being stunned for a number of seconds equal to the margin of your failure, plus 2d. On a critical failure, the victim faints, and cannot be revived for the margin of failure plus 1d minutes. Hope the thing that scared you isn’t hungry . . .
Re: How the Gurps System works
Sense Rolls
“Sense rolls” include Vision rolls, Hearing rolls, and Taste/Smell rolls. To notice something using a given sense, roll against your Perception score.
Comprehension Rolls: A successful Sense roll means you noticed something. That is often sufficient, but in some cases, the GM may require a second roll to understand what you have sensed; e.g., to realize that the “owl hoot” you heard is really an Indian warrior, or that the faint scent you noticed belongs to the flower of a man-eating plant. This roll is against IQ for details that anyone could figure out, or against an appropriate skill if the significance would be lost on anyone but an expert.
Danger Sense: If you have the Danger Sense advantage and fail a Sense roll or comprehension roll to notice something dangerous, the GM will secretly make a Perception roll for you. On a success, you sense the danger anyhow!
Vision
Make a Vision roll whenever it is important that you see something. When you try to spot something that is deliberately hidden, the GM may treat this roll as a Quick Contest against a concealment skill (Camouflage, Holdout, etc.), and may allow – or require – a skill such as Observation or Search to replace Perception for the roll.
Hearing
Make a Hearing roll whenever it is important that you hear a sound. The GM will often require a separate IQ roll to make out speech, especially in a foreign language. When you try to hear someone who is attempting to move silently, the GM may treat this roll as a Quick Contest against his Stealth skill. If you are actively listening for such activity, the GM may allow you to substitute Observation skill for Perception.
Taste/Smell
Taste and smell are two manifestations of the same sense. Make a Taste roll to notice a flavor, or a Smell roll to notice a scent.
“Sense rolls” include Vision rolls, Hearing rolls, and Taste/Smell rolls. To notice something using a given sense, roll against your Perception score.
Comprehension Rolls: A successful Sense roll means you noticed something. That is often sufficient, but in some cases, the GM may require a second roll to understand what you have sensed; e.g., to realize that the “owl hoot” you heard is really an Indian warrior, or that the faint scent you noticed belongs to the flower of a man-eating plant. This roll is against IQ for details that anyone could figure out, or against an appropriate skill if the significance would be lost on anyone but an expert.
Danger Sense: If you have the Danger Sense advantage and fail a Sense roll or comprehension roll to notice something dangerous, the GM will secretly make a Perception roll for you. On a success, you sense the danger anyhow!
Vision
Make a Vision roll whenever it is important that you see something. When you try to spot something that is deliberately hidden, the GM may treat this roll as a Quick Contest against a concealment skill (Camouflage, Holdout, etc.), and may allow – or require – a skill such as Observation or Search to replace Perception for the roll.
Hearing
Make a Hearing roll whenever it is important that you hear a sound. The GM will often require a separate IQ roll to make out speech, especially in a foreign language. When you try to hear someone who is attempting to move silently, the GM may treat this roll as a Quick Contest against his Stealth skill. If you are actively listening for such activity, the GM may allow you to substitute Observation skill for Perception.
Taste/Smell
Taste and smell are two manifestations of the same sense. Make a Taste roll to notice a flavor, or a Smell roll to notice a scent.