GURPS Core Resources: Quick Start

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This section is a brief guide to the whole GURPS game system. Although the system has many rules that span many individual pages, most of that is detail, “color,” and special cases. The game system is actually easy.

There are only three basic mechanics in GURPS:

1) Success Rolls. A success roll is a die roll made when you need to test (roll against) one of your skills or attributes, such as Strength to stop a heavy door from closing. The only dice used in GURPS are six-sided dice; you roll three of them for a Success Roll. If your roll is less than or equal to the skill or ability you are testing, you succeed. Otherwise, you fail. For instance, if you're rolling against Strength and your ST level is 12, a roll of 12 or less succeeds.

Sometimes you will have modifiers to a roll. For instance, if you were trying to stop a very heavy door from closing, you might have to roll against Strength - 2 (or ST - 2 for short.) In that case, with an ST of 12, you'd need to roll a 10 or less. Rolling a 10 or less is harder than rolling a 12 or less, just as stopping a very heavy door is harder than stopping a normal door.

For an especially easy task, you might get a bonus to your attempt. You might roll against Animal Handling + 4 to make friends with a very friendly dog. If your Animal Handling skill is 12, this means you would have to roll a 16 or less to succeed. Making a roll of 16 or less is easier than making a roll of 12 or less, because a friendly dog is easy to deal with.

2) Reaction Rolls. A reaction roll is a roll made by the Game Master (or GM) to determine how his nonplayer characters (NPCs) react to the player characters. This roll is always optional; the GM may predetermine reactions. But sometimes it's more fun to let the dice control the reactions.

To check reactions, the GM rolls 3 dice and consults the Reaction Table. The higher his roll, the better the NPCs will react, and the better the treatment they will give the NPCs.

Many traits give reaction modifiers that add to or subtract from reaction rolls. If you have a +2 reaction due to your good looks, the GM will add 2 to any reaction roll made by someone who can see you. This is likely to improve the way they behave towards you!

3) Damage Rolls. A damage roll is a roll made in a fight, to see how much harm you did to your foe. Damage rolls use the dice+adds system (see below.)

Many things can affect the final injury inflicted by your attack. Armor reduces the damage received by the wearer. Certain attacks do extra damage if they get through armor. 'Critical hits' can do extra damage. All these things are explained in the combat rules. But the combat system is 'modular'; you can use all the rules for a complex, detailed, realistic combat simulation - or just the basics for a quick game.

There's another important system - but you don't need to know it to start with. It's the character creation system. The GM will give each player a number of points to spend on his character. High attribute levels cost points, as do advantages and skills. Disadvantages, such as Greed and Berserk, are also available; these give you extra points.

These rules let you do all your calculations during play, and list them on your character sheet. That way, you don't have to bother with calculations during play!

Got all that? Good. That's enough to play GURPS. The rest is just detail. Have fun.

GURPS uses the following mathematical conventions:

GURPS uses six-sided dice only. All 'success rolls,' and most other rolls, require you to throw three dice (“3d”) at once, add up the numbers on the dice, and compare the total to a “target number.”

To figure combat damage, and for many other things, GURPS uses the “dice+adds” system. If a weapon does “4d+2” damage, this is shorthand for “roll 4 dice and add 2 to the total.” Likewise, “3d-3” means “roll 3 dice and subtract 3 from the total.”

If you see just “2d,” that means “roll two dice.” For instance, if an adventure says, “The base is guarded by 5d human soldiers and 2d+1 robots,” that's short for, “Roll five dice for the number of human guards at the base. Then roll two dice, and add 1, for the number of robots.”

For really huge numbers, dice can be multiplied. For instance, “2dx10” means “roll 2 dice and multiply by 10.”

A mathematical formula is often the best way to ensure that a rule is fair, realistic, or universal. But formulas sometimes yield inconvenient fractions. Except where instructed otherwise, round off fractions as follows:

Round up for point costs. When you modify a point cost by a percentage, or multiply it by a factor, round all fractions up. For instance, a 25% enhancement to a 15-point ability would result in 18.75 points, which would round to 19 points. For negative numbers, “up” means “in the positive direction”; e.g., if you multiply -7 points by 1/2 to get -3.5 points, round the result to -3 points.

Round down for character feats and combat results. When you do math to determine what a character can do - how much he can lift, how far he can jump, etc. - or to calculate injury or other combat results, round all fractions down. For instance, for an attack that inflicts 3 points of injury with a 50% damage bonus, round down from 4.5 to 4 points.

Exceptions and special cases (such as 'round to the nearest whole number' or 'do not round off') are noted explicitly with the relevant rule.

This is a quick way to convert things from imperial system to metric system; it includes an approximation - easy to do in your head and good enough for most gaming - and the real equivalent, for those times when exact is important.

Temperature: When dealing with changes in temperature, one Fahrenheit degree is 5/9 the size of a degree Celsius. So a change of 45 degrees Fahrenheit is equal to a change of 25 degrees Celsius. To convert actual thermometer readings, subtract 32 from the Fahrenheit temperature and multiply the result by 5/9. So 95 degrees Fahrenheit is 5/9 of (95-32), or 5/9 of 63, or 35 degrees Celsius.