Introduction
The GURPS System
What the game is, how the system works, and the three fundamental mechanics you'll use every time you play.
What Is GURPS?
GURPS stands for Generic Universal RolePlaying System — originally a working code name that stuck. Now in its Fourth Edition, the name is more appropriate than ever. Each word is a design principle, not just a label.
GURPS uses plain English units throughout — distances in feet and miles, times in minutes and seconds. This makes it straightforward to import material from other games or supplements. If you see an interesting adventure for a different system, you can translate it directly.
GURPS demands that players actually think during the adventure, rather than simply consulting dice results. Each character is a uniquely crafted creation — not a class selection.
That depth is also what makes it so memorable. The more you put in, the more you get back.
What Is Roleplaying?
In a roleplaying game, each player takes the part of a character participating in a fictional adventure. A referee — the Game Master (GM) — sets the scene, controls the world, and plays the non-player characters the party meets. The GM describes what characters see and hear; players describe what they do in response; the GM describes the consequences. And so on.
Roleplaying is not purely competitive. The party usually succeeds or fails as a group. It is also one of the most creative forms of entertainment: unlike passive media, the audience is the story. The GM provides the raw material, but the final shape comes from the players themselves.
The GM determines outcomes in three ways:
- Arbitrarily — for the best story, when a dice roll would feel forced or anticlimactic.
- By specific rules — to determine what is realistically possible given the character's abilities.
- By rolling dice — for interesting random results that keep even the GM surprised.
Knowing when to use each is the heart of good GMing.
Mini-Glossary
These are the core terms used throughout both volumes. A complete glossary appears at the back of the book. The definitions here are enough to understand the Quick-Start rules without flipping pages.
| Term | Definition | See Also |
|---|---|---|
| advantage | A useful trait that gives you an "edge" over someone with comparable attributes and skills. | Chapter 2 |
| attributes | The four core numbers — ST, DX, IQ, HT — that rate a character's most basic abilities. Higher is always better. | pp. 14–15 |
| cinematic | A style of play where story needs outweigh realism, even when that produces improbable results. | p. 488 |
| d | Short for "dice." "Roll 3d" means roll three ordinary six-sided dice and add them up. | Conventions, below |
| Dexterity (DX) | Attribute measuring agility and coordination. Controls most physical and combat skills. | p. 15 |
| disadvantage | A problem that renders you less capable — but returns points for you to spend elsewhere. | Chapter 3 |
| enhancement | An extra capability added to a trait. Increases its point cost by a percentage. | pp. 102–109 |
| Fatigue Points (FP) | Measures resistance to exhaustion from physical exertion, casting spells, and similar effort. | p. 16 |
| Health (HT) | Attribute measuring physical grit, vitality, and resistance to disease and injury. | p. 15 |
| Hit Points (HP) | Measures ability to absorb physical damage before falling unconscious or dying. | p. 16 |
| Intelligence (IQ) | Attribute measuring brainpower, common sense, and creativity. Controls most mental and social skills. | p. 15 |
| limitation | A restriction on the use of a trait. Reduces its point cost by a percentage. | pp. 110–117 |
| point | The currency of character creation. Spent to buy traits. Written in brackets — e.g., Combat Reflexes [15] costs 15 points. | p. 10 |
| prerequisite | A trait you must already have before learning another. For skills, you need at least 1 point in it. | p. 169 |
| skill | A number defining your trained ability in an area of knowledge or class of tasks. | Chapter 4 |
| Strength (ST) | Attribute measuring physical muscle and bulk. Determines basic damage and carrying capacity. | p. 14 |
| trait | Any advantage, attribute, disadvantage, skill, or other character building block that affects play and costs points. | Throughout |
The Three Game Mechanics
The entire GURPS system rests on three types of die rolls. Everything else — combat, social interaction, exploration, magic — is built on top of these. Learn these three, and you can begin playing immediately.
GURPS is a roll-under system — the opposite of what D&D players are used to. In GURPS, a modifier of +2 means your effective target number goes up by 2, which is a good thing because you need to roll equal or under it. A modifier of −2 means your target drops by 2, making success harder. So: +Number = beneficial and −Number = a penalty. Keep this in mind throughout every section that follows.
The character creation system is a fourth important element, but you do not need it during play — all the relevant calculations are done beforehand and recorded on your character sheet.
Success Rolls
A success roll is the most common roll in GURPS. Any time a character attempts something with a meaningful chance of failure, the player rolls 3d (three six-sided dice) and compares the total to a target number — usually a skill level or attribute.
Roll 3d > target number → FAILURE
Roll 17 or 18 → AUTOMATIC FAILURE (no matter how high the target)
Roll 3 or 4 → CRITICAL SUCCESS (no matter what)
Modifiers
The GM applies modifiers to the target number based on how hard the task is. A harder task lowers the effective target; an easier one raises it. These are written as Skill±N. Remember: +N raises your target (easier), −N lowers it (harder).
Your ST is 12. Normally you'd roll against ST 12. But the door is very heavy — the GM calls for ST−2. Your effective target drops to 10. You must roll 10 or less on 3d to succeed.
Your Animal Handling is 12. The dog is unusually friendly, so the GM gives +4. Your effective target is 16. Rolling 16 or less on 3d succeeds — easy task, high probability of success.
Base Skill vs. Effective Skill
Your printed skill level is your base skill — your odds under normal conditions, before any situational modifiers are applied. After all modifiers are factored in, the final number you actually roll against is your effective skill. Think of base skill as what's on your character sheet, and effective skill as what you're actually rolling against at any given moment.
Mira has Climbing-13 written on her sheet. That 13 is her base skill — it never changes.
She tries to scale a rain-soaked stone wall while wearing light armor. The GM applies:
- −3 for wet, slippery stone
- −1 for encumbrance from armor
Her effective skill = 13 − 3 − 1 = 9. She must roll 9 or less on 3d to succeed. Base skill didn't change — only the effective skill shifted based on circumstances.
Rolling 17 or 18 always fails, so base skill above 16 doesn't improve normal success odds. The value of high skill is in absorbing penalties. A difficult lock gives −6. With Lockpicking-15, your effective skill drops to 9. With Lockpicking-23, you're still at 17 — near-certain success despite the penalty.
Think of each point of base skill above 10 as insurance against penalties. With Stealth-12 and −8 in penalties from daylight and open terrain, your effective skill is 4 — barely possible.
With Stealth-18 and the same −8, you're at 10 — a coin flip. Same situation, very different character.
Reaction Rolls
When the player characters meet an NPC and the GM wants to determine how that NPC feels about them, he rolls 3d and consults the Reaction Table. The higher the roll, the more favorably the NPC reacts.
This roll is always optional. The GM may predetermine reactions for story reasons — reaction rolls exist to add unpredictability and to make character traits feel consequential.
Always tell your GM when you have a relevant trait before the dice hit the table. Passive traits like Appearance and Reputation apply automatically — but it's your job to remind the GM they exist.
Don't assume the GM is tracking every advantage on your sheet during a social encounter.
Many traits directly modify reaction rolls — even if you never actively use them. These modifiers apply automatically whenever an NPC forms an opinion of your character. Examples include:
- Appearance — Beautiful or Handsome characters receive +4 or +4/+2 reaction bonuses from those attracted to their gender. Ugly or Hideous appearances impose negative reactions.
- Charisma — Gives +1 per level to all reaction rolls, from everyone, all the time.
- Voice — Adds +2 to any reaction roll where your character is speaking and can be heard.
- Reputation — Can be positive or negative, and only applies to people who recognize you. A hero renowned in their home city gets a +3 bonus there — and perhaps none elsewhere.
- Status — Affects reactions from people who respect social rank. High Status impresses some NPCs and antagonizes others.
- Odious Personal Habits — Imposes a −1 to −3 reaction penalty from anyone who encounters the habit. Even NPCs who've never met you before will be put off.
Some traits affect NPC reactions whether or not you actively use them — Appearance, Odious Personal Habits, and Reputation all work passively. You don't have to "activate" them. This means even a character who never tries to be social will still be affected by reaction rolls based on how they look, smell, or are known.
Damage Rolls
When a character successfully hits in combat, a damage roll determines how much harm was done. Damage rolls use the dice+adds notation described in Dice Conventions below.
Several things modify final injury:
- Armor — reduces the damage received by its Damage Resistance (DR) value.
- Armor Divisors — some attacks penetrate armor more effectively, dividing the target's DR before applying damage.
- Damage Type — cutting, impaling, crushing, etc. Each type applies a multiplier to injury after armor is subtracted.
- Critical Hits — a roll of 3 or 4 on a success roll produces a critical hit, potentially doubling damage or causing extra effects.
A sword doing 2d+3 rolls between 5 and 15. Against DR 6 armor, a roll of 8 (total 11) does only 5 injury — that same roll unarmored is 11 injury.
Armor often matters more than extra HP. HP keeps you alive after damage lands; DR stops it from landing at full force.
The combat system is modular. By default, you use only the core rules for a fast game:
- Default: Roll dice+adds for damage, subtract target's DR, apply remainder as injury.
- Default: Damage types (cutting ×1.5, impaling ×2, crushing ×1) are the only multipliers.
Optional layers you can add for more detail:
- Bleeding — optional rule; injured characters may continue losing HP each turn.
- Shock — optional rule; taking injury gives a penalty to your next action equal to the injury taken (max −4).
- Knockback — optional rule; large hits may physically push the target back.
- Hit Locations — optional rule; target specific body parts for additional effects and penalties.
All optional rules are clearly labelled in the source book. If it's not listed as optional, it's in by default.
A weapon does 2d+3 damage. Roll 2 dice and add 3. Roll a 7 → total damage is 10. If the target's armor absorbs 4 points (DR 4), the final injury is 6 hit points.
Dice Conventions
GURPS uses six-sided dice only. Every success roll uses exactly three dice 3d. Damage and other variable quantities use the dice+adds notation.
| Notation | Meaning | Example Result |
|---|---|---|
| 3d | Roll three six-sided dice, add the results. Used for all success rolls. | Range: 3–18 |
| 4d+2 | Roll four dice, add 2 to the total. Standard dice+adds format. | Range: 6–26 |
| 3d−3 | Roll three dice, subtract 3 from the total. Result can reach 0 or below. | Range: 0–15 |
| 2d×10 | Roll two dice and multiply the result by 10. Used for very large numbers. | Range: 20–120 |
| 5d | Roll five dice and add. Can appear in encounter tables or large damage values. | Range: 5–30 |
A weapon does 2d+4 cutting damage. Roll 2 dice: say you get a 3 and a 5, total 8. Add 4: the attack does 12 points of cutting damage before armor is applied.
An adventure reads: "The base holds 5d soldiers and 2d+1 robots." Roll 5 dice for the soldiers, then roll 2 dice and add 1 for the robots. Every run of this encounter will be different.
Rounding Rules
Math in GURPS often produces fractions — especially when applying percentage-based enhancements and limitations to point costs. Two different rounding rules apply depending on context, and getting them right matters.
| Context | Rule | Example |
|---|---|---|
| Point costs | Round up — fractions become the next whole number. For negative costs, "up" means toward zero. | 25% enhancement on 15-pt trait → 19 pts −7 pts × ½ → −3 pts |
| Character feats & combat | Round down — drop the fraction entirely. Applies to lifting, jumping, damage, and all physical results. | 3 injury + 50% bonus → 4 pts of injury |
You want to apply a +25% enhancement to an advantage that normally costs 15 points. Here's the full calculation:
- Start with the base cost: 15 pts
- Calculate the enhancement value: 15 × 0.25 = 3.75 pts
- Add to the base: 15 + 3.75 = 18.75 pts
- Round up (it's a point cost): 19 pts
Now the same for a −50% limitation on a −7 point disadvantage:
- Start with the base cost: −7 pts
- Multiply by ½: −7 × 0.5 = −3.5 pts
- Round up toward zero (negative cost, so "up" = less negative): −3 pts
An attack deals 3 points of injury, and a rule says to apply a +50% bonus to it:
- Base injury: 3 pts
- Calculate the bonus: 3 × 0.5 = 1.5 pts
- Add to base: 3 + 1.5 = 4.5 pts
- Round down (it's a combat result): 4 pts of final injury
When a specific rule rounds differently — to the nearest whole number, or not at all — it says so explicitly in the text. If no instruction is given, use the two rules above: costs round up, results round down.
Metric Conversions
GURPS uses imperial units throughout — distances in yards, weight in pounds. The table below shows what those numbers tie to in actual play and provides metric equivalents for groups who prefer them.
You already know feet and pounds — that part is the same. The main shift is that GURPS measures combat distance in yards, not feet.
- 1 yard = 3 feet. It's the same as one of D&D's 5-foot squares, roughly. GURPS just uses the slightly larger yard as the basic unit.
- In D&D, moving one square costs 5 feet of movement. In GURPS, each Basic Move point lets you move 1 yard per second (a combat turn). A character with Move 5 travels 5 yards — about 15 feet — per turn.
- A typical "room" in GURPS combat is 4–6 yards across — that's 12–18 feet, similar to a D&D medium room.
- Weight works the same (pounds). The difference is GURPS uses your Basic Lift (derived from ST) as the encumbrance threshold rather than a flat slot system.
- Volume (gallons, quarts) matters when buying or carrying liquid supplies — food, water, potions, oil. It's not combat-relevant but comes up in wilderness and dungeon logistics.
- Time units (seconds, minutes, hours) are identical between systems.
| Imperial | In Feet | Game Metric | Used in GURPS for… |
|---|---|---|---|
| 1 inch | — | 2.5 cm | Weapon dimensions, fine measurements |
| 1 foot | 1 ft | 30 cm | Height descriptions, short distances |
| 1 yard | 3 ft | 1 meter | Combat range, movement, map distance |
| 1 mile | 5,280 ft | 1.5 km | Travel distance, ranged weapon maximums |
| 1 pound | — | 0.5 kg | Encumbrance, weapon/armor weight |
| 1 ton | — | 1 metric ton | Vehicle/structure weight |
| 1 gallon | — | 4 liters | Water supply, alchemical quantities |
| 1 quart | — | 1 liter | Rations, potions, oil flasks |
| 1 ounce | — | 30 grams | Coin weight, fine goods, poisons |
| 1 cubic inch | — | 16 cu. cm | Dense materials, gemstone volume |
| 1 cubic yard | — | 0.75 cu. m | Digging, magical area volumes |
If your group plays with Celsius temperatures (common in metric-using countries or if the source material lists °C), here is the conversion in plain steps:
- Step 1: Subtract 32 from the °F value.
- Step 2: Multiply the result by 0.556 (or use the fraction 5/9).
Example — 95°F to Celsius:
- 95 − 32 = 63
- 63 × 0.556 ≈ 35°C
If your game simply uses Fahrenheit — which most English-language GURPS material does — you will never need this formula. It is here only for groups using metric source material.
The highlighted rows — yard, mile, and pound — are the three measurements that come up constantly in play. Memorise those three and you are covered for 95% of sessions. Everything else you can look up.
Chapter Quiz
An infinite draw from a bank of 50+ questions covering every concept in this Introduction — vocabulary, the roll-under system, point cost calculations, effective skill scenarios, damage math, and dice notation. Questions shuffle continuously; answer as many as you like. No rounds, no score — just the knowledge check.
Point costs for enhancements and limitations are applied as a percentage of the base cost. Two formulas cover every case:
- Enhancement (+X%): base × (1 + X/100) → e.g. 10 pts at +30% = 10 × 1.30 = 13 pts
- Limitation (−X%): base × (1 − X/100) → e.g. 10 pts at −30% = 10 × 0.70 = 7 pts
Always round up if the result is fractional — 9.2 pts becomes 10 pts. A basic calculator handles all of this in seconds.