Role-playing games of the 1970s and 1980s, such as Dungeons & Dragons, used random numbers generated by dice rolls to assign statistics to player characters. GURPS, in contrast, assigned players a specified number of points with which to build their characters. Together with the HERO System, GURPS was one of the first role-playing games in which characters were created by spending points to get attributes, skills, and advantages (such as the ability to cast magic spells). Additional points can be obtained by accepting lower-than-average attributes, disadvantages, and other limitations. This approach remains popular in role-playing games, in part due to the success of GURPS.
GURPS' emphasis on its "generic" aspect has proven to be a successful marketing tactic, as many game series have source engines which can be retrofitted to many styles. GURPS' approach to versatility includes using real world measurements wherever possible ("reality-checking" is an important part of any GURPS book). This allows players to fairly trivially convert things from the real world, other games or their imagination to GURPS statistics.
GURPS also benefits from the many dozens of worldbooks describing settings or additional rules in all genres including science fiction, fantasy, and historical. Many popular game designers began their professional careers as GURPS writers, including C.J. Carella, Robin Laws, S. John Ross, and FUDGE creator Steffan O'Sullivan. It is sometimes stated that a large contingent of people who do not play GURPS purchase GURPS supplements because of the talented and creative writers. GURPS worldbooks set in historical periods can often be used as reference books as they usually include a bibliography suggesting additional sources.
The immediate mechanical antecedent of GURPS was The Fantasy Trip (TFT), an early role-playing game written by Steve Jackson for the company Metagaming Concepts. Several of the core concepts of GURPS first appeared in TFT, including the inclusion of Strength, Dexterity and Intelligence as the core abilities scores of each character.
In 1990 GURPS intersected part of the hacker subculture when the company's Austin, Texas, offices were raided by the Secret Service. The target was the author of GURPS Cyberpunk in relation to E911 Emergency Response system documents stolen from Bell South. The incident was a direct contributor to the founding of the Electronic Frontier Foundation. A common misconception holds that this raid was part of Operation Sundevil and carried out by the FBI. Operation: Sundevil was in action at the same time, but it was completely separate. See Steve Jackson Games, Inc. v. United States Secret Service.
Steve Jackson Games released GURPS Fourth Edition at the first day of Gen Con on August 19, 2004. It promised to simplify and streamline most areas of play and character creation. The changes include an edited and rationalized skill list, clarification of the difference between ability from experience and from inborn talent, more detailed language rules, and revised technology levels. Designed by Sean Punch, the Fourth Edition was sold as two full-color hardcover books.
In principle, a Game Master can balance the power of foes to the abilities of the player characters by comparing their relative point values.
Having only four attributes is arguably much simpler compared to other role-playing games which can have several main stats that cover more defined abilities. Each attribute has a number rating assigned to it. Normally they begin at 10, representing typical human ability, but can go as low as 1 for nearly useless, to 20 (or higher) for superhuman power. Anything in the 8 to 12 range is considered to be in the "normal" (more or less average) area for humans. Basic attribute scores of 6 or less are considered crippling — they are so far below the human norm that they are only used for severely handicapped characters. Scores of 15 or more are described as amazing — they are immediately apparent and draw constant comment.
Players assign these ratings spending character points. The higher the rating the more points it will cost the player, however, assigning a score below the average 10 gives the player points back to assign elsewhere. Since almost all skills are based on Dexterity or Intelligence, those attributes are twice as expensive (or yield twice the points, if purchased below 10). In earlier editions (pre 4th Edition) all attributes followed the same cost-progression, where higher attributes cost more per increase than attributes close to the average of 10.
Attribute scores also determine several secondary characteristics. The four major ones are each directly based on a single attribute:
In earlier GURPS editions (that is, prior to the 4th Edition) Hit Points were based on HT and Fatigue Points were based on ST.
A player can select numerous Advantages and Disadvantages to differentiate the character; the system supports both mundane traits (such as above-average or below-average Wealth, Status and Reputation) as well as more exotic special abilities and weaknesses. These are categorized as physical, mental or social, and as exotic, supernatural, or mundane. Advantages benefit the character and cost points to purchase. Selecting Disadvantages returns character points and allows players to limit their characters in one way in exchange for being more powerful or gifted in other areas. Disadvantages include such positive attributes as honesty and truthfulness which limit the way a character is played. There are also many Perks and Quirks to choose from which give a character some personality. Perks (minor Advantages) and Quirks (minor Disadvantages) benefit or hinder the character a bit, but they mostly add role-playing flavor.
Enhancements and limitations can tailor an advantage or disadvantage to suit creative players. These modify the effects and point cost of advantages and disadvantages. For example, to create a "dragon's breath" attack, a player would select the Innate Attack ability (the ability that allows a player to perform an attack most humans could not), and select burning attack 4D (normally 20 points). Then, the player would modify it as follows: cone, 5 yards (+100%); limited use, 3/day (-20%); reduced range, x1/5 (-20%). The final percentage modifier would be +60%, making the final cost 32 points. This addition to the system greatly increases its flexibility while decreasing the number of specific advantages and disadvantages that must be listed. Finally, mitigators can themselves tailor advantages and disadvantages (see GURPS Bio-Tech for such an example).
The availability of skills depends on the particular genre the GURPS game is played. For instance, in a generic medieval fantasy setting, skills for operating a computer, or flying a fighter jet would not normally be available. Skills are rated by level, and the more levels purchased with character points, the better the characters are at that particular skill relative to their base attribute.
Skills are categorized by difficulty: Easy, Average, Hard, and Very Hard. Easy skills cost fewer points to purchase levels in, while Hard skills cost more. A player can generally purchase a skill for his character at any level he or she can afford. The lower you choose the fewer points it costs to buy the skill, and the higher you go, the more points it costs. Some skills have default levels, which indicate the level rating a character has when using that skill untrained (i.e. not purchased). For example, a character with a Dexterity of 12, is using the Climbing skill untrained. Climbing has a default of DX-5 or ST-5, which means that using the skill untrained gives him a Climbing skill level of 7 (12-5) if he tied it to the Dexterity stat. If the character had a higher Strength stat, he could have a better chance of success if they tied the Climbing skill there instead.
Some skills also have a Tech Level (TL) rating attached to them, to differentiate between Skills that concern similar concepts, but whose tasks are accomplished in different ways when used with differing levels of technology. This helps during time traveling scenarios, or when characters are forced to deal with particularly outdated or advanced equipment. For instance, a modern boat builder's skills will be of less use if he is stuck on a desert island and forced to work with primitive tools and techniques. Thus, the skills he uses are different when in his shop (Shipbuilding/TL8) and when he is on the island (Shipbuilding/TL0).
Making stat and skill checks in GURPS is the reverse of the mechanics of most other RPGs, where the higher the total of the die roll, the better. GURPS players hope to roll as low as possible under the tested statistic's rating or skill's level. If the roll is less than or equal to that number, the check succeeds. There is no "target number" or "difficulty rating" set by the Game Master, as would be the case in many other RPG systems. Instead the GM will apply various modifiers to add or subtract to the skill level. In this way, positive modifiers increase the chance for success by adding to the stat or skill level you must roll under while negative modifiers deduct from it, making things more difficult.
For example: a player makes a pick pocketing test for her character. The character has a Pickpocket skill with a level of 11. Under normal circumstances - i.e., under an average stressful situation, according to the manual - the player must roll an 11 or less for the character to succeed. If the player rolls above 11, then the character has failed the attempt at pick pocketing.
There are some exceptions for very high or low rolls, deemed criticals. No matter the level of the skill, a die roll of 18 is always a critical failure, and a roll of 3 or 4 is always a critical success (a roll of 17 is a critical failure as well, unless the character relevant skill level is 16 or more). The Game Master may decide in such cases that, in first case (a roll of 18, or 10+ over the modified skill level), the character has failed miserably and caused something disastrous to happen or, in the other case, that he or she succeeds incredibly well and gains some benefit as a result.
There are two kinds of attacks: Melee (possibly with hand-to-hand weapons, or unarmed combat) and Ranged (bows, guns, thrown weapons, some Innate Attacks, etc.). Attacks made by a character are checked against their skill with the particular weapon they carry. For instance, if a character is using a pistol, as with any other skill, it is beneficial to have a high level in the Guns skill. Like any other skill check, a player must roll equal to or less than the level of the skill to succeed. Failure means a miss, success scores a hit. Similarly, critical hits mean that the blow might inflict significantly more damage to its target; critical misses may lead to a rather unpleasant and unexpected event (such as dropping the weapon or hitting the wrong target). Attack modifiers are set by the GM when factoring in things like body armor and cover that make a successful strike more difficult.
After a successful attack, except in the case of a critical hit, the defender usually gets a chance to avoid the blow. This is called an Active Defense, and takes the form of a Dodge (deliberate movement out of the perceived path of the attack), Parry (attempt to deflect or intercept the attack with a limb or weapon), or Block (effort to interpose a shield or similar object between the attack and the defender's body). Unlike many RPG systems, an Active Defense is an unopposed check, meaning that in most cases, the success of an attack has no effect on the difficulty of the defense. Dodge is based on the Basic Speed characteristic, while Parry and Block are each based on individual combat skills, such as Fencing, Karate, or Staff for Parry, and Shield or Cloak for Block.
Certain skills, attributes and equipment, when strung together, can be used to great effect. Let us say a gunslinger from the Old West is facing a foe; he can use the Combat Reflexes ability to react before his enemy, the Fast-Draw(Pistol) skill to get his two guns out, the Gunslinger ability to allow him to skip the aiming step, and the Dual-Weapon Attack(Pistol) skill to fire both his guns at once. This would have taken around 6 turns, if he had none of these skills.
When damage is inflicted upon characters, it is deducted from their Hit Points, which are calculated with the Strength stat (prior to GURPS 4th Edition, Hit Points were derived from the Health stat). Like most other RPGs, a loss of hit points indicates physical harm being inflicted upon a character, which can potentially lead to death. GURPS calculates shock penalties when someone is hit, representing the impact it causes and the rush of pain that interferes with concentration. Different weapons can cause different 'types' of damage, ranging from crushing (a club or mace), impaling (a spear or arrow), cutting (most swords and axes), piercing (bullets), and so on.
One peculiarity about loss of Hit Points is that in GURPS, death is not certain. While a very high amount of total HP loss will cause certain death, there are also several points at which a player must successfully roll HT, with different grades of failure indicating character death or a mortal injury.
Depending on the nature of the attack, there will sometimes be additional effects.
GMs are free to distribute experience as they see fit. This contrasts with some traditional RPGs where players receive a predictable amount of experience for defeating foes. The book recommends providing 1-3 points for completing objectives and 1-3 points for good role-playing per game session.
Advancement can also come through study, work, or other activities, either during game play or between sessions. In general, 200 hours of study equals one character point which can be applied for the area being studied. Self-study and on the job experience take more time per character point while high tech teaching aids can reduce the time required.
Some intensive situations let a character advance quickly, as most waking hours are considered study. For instance, characters travelling through the Amazon may count every waking moment as study of jungle survival, while living in a foreign country could count as eight hours per day of language study or more.
GURPS For Dummies, a guidebook by Stuart J. Stuple, Bjoern-Erik Hartsfvang, Adam Griffith, was published in 2006. ISBN 0-471-78329-3
GURPS references are a running joke in the webcomic Something Positive. Characters often wear GURPS shirts, soda machines dispense "GURPS cola" and the local gaming store carries fictitious games such as "GURPS Sixteenth Century French Drama".