|Players||2 or more|
|Setup time||1–14 days|
|Playing time||1–10 weeks|
|* Targets are randomly assigned.|
Assassin (also Gotcha, Assassins, KAOS (Killing as organized sport), Juggernaut, Battle Royal, Paranoia, Killer, Elimination, or Circle of Death) is a live-action game. Players try to eliminate each other from the game using mock weapons in an effort to become the last surviving player.
Assassin is particularly popular on college campuses; several universities have a dedicated "Assassins' Guild" society, which organizes games for their members. Game play occurs at all hours and in all places unless otherwise disallowed by the rules. Since an elimination attempt could occur at any time, successful players are obliged to develop a healthy degree of watchful paranoia.
The Assassin game has several published variants, such as the Steve Jackson rules book Killer: The Game of Assassination, first published in 1982, and different guilds tend to create their own sets of rules and procedures. As such, the specific style of play is likely to vary between one group and the next.
Game hosts (also called umpires or referees) begin by advertising that a game is being set up and instruct potential players to send in their personal details. Once enough players have signed up, the game host assigns targets to the players. A player is usually told the personal details of their target as collected by the game host. The aim of the game is for players to track down and eliminate their targets until only one player remains. When a player eliminates their target, they get the victim's target(s). If only one player remains, the game is over.
Oxford University plays by a ruleset where the game runs for a week and the players respawn, usually after 12 hours, the aim of the game is to collect as many points from kills as possible. The respawn means events are organised during the game to capture specific points.
Eliminations ("kills") remove a target from the game. What constitutes an elimination depends upon the particular rules set up by the game host. Eliminations might include hitting the target with an airsoft gun, striking them with a toy plastic lightsaber, or putting a dash of hot sauce ("poison") in the target's food.
Some rules establish safe-zones. A safe-zone is a place that protects a player from elimination. Safe-zones are declared by game hosts. At a university, safe zones might include classrooms during class periods.
Under some rulesets, the presence of witnesses (or the presence of witnesses above a certain number) will either invalidate the kill or expose the killer to "penalties", like additional assassins being dispatched to target him or her.
Game hosts might assign certain items to be worn or actions to be performed that protect the wearer or performer from elimination. These items or actions are called safeties. The safety can last for one specific day or last for the duration of the game.
Some games have "police forces", sometimes composed of eliminated players, whose job is to track down rule breakers. Some have time limits on eliminations and penalize players who are behind schedule in killing their targets.
Methods of elimination
Generally, elimination is carried out using items and methods that cause no actual damage and, in many cases, cannot be mistaken by bystanders for real weapons or acts of violence.
In a direct elimination, a player uses a fake weapon to touch his or her target.
The most common ranged weapons are water pistols, NERF-type weapons, and rubber band guns. Other weapons include tennis balls, balled-up socks, or rubber bands fired by hand. Some rulesets simply make "water" a weapon, whether splashed with bare hands, conveyed by water balloon, or fired from a water gun. Basilisk rules count simply sighting one's target as a successful assassination. Some rulesets require photographic proof that a true sighting occurred.
Melee weapons are typically fake stabbing weapons. Melee weapons are more easily concealed than ranged weapons but require more stealth to employ effectively. Melee weapons must touch a player's body to eliminate them. Common examples of melee weapons are cardboard and plastic knives, plastic lightsabers, spoons, and toothbrushes. Sharpie markers can be used as melee weapons by marking on a player's exposed skin. Stickers can be used as well, by sticking them to a player's body.
In an indirect elimination, a player plants an object where his or her target will be eliminated by it or changes his or her target's environment in a specific way, as defined by the variant's rules, that results in an elimination. Some variants allow "poison", which can be implemented by adding strong flavors such as Tabasco sauce to the victim's food or a piece of paper placed underneath the victim's food with the word poison written on it. Another form is the use of a "black spot". If a player opens a paper, sealed with tape, staples or any other of such, and there is a black spot inside the player is eliminated.
Some variants allow "bombs", which may be implemented in various ways. Some require the bomb to "go off" in some way and hence might use alarm clocks or other timers. One technique may be to "e-bomb" a target by either using an e-mail or instant messenger to send a file to a target in order to kill them. This attachment may be a word document, audio file, or an image that shows that the target is dead and the assassin that killed them. Another technique is the "car bomb", where the assassin puts a tape or CD in the victim's car audio system. When the victim starts the car and audio, they will hear the assassin saying that they were just "car bombed". Another car-bomb variant allows one to shoot and kill the person while they are in the car by striking the car rather than the person inside, if using the Nerf Rocket Launcher or equivalent. An assassin may also bomb a victim by sending him or her a package in the mail with a dart or letter saying "You're Bombed." The victim is eliminated as soon as she or he opens the package and reads the note.
Other weapons include poisonous animals (usually a rubber spider, snake, or lizard placed within the victim's backpack or book) and various manners of simulated traps. If an innocent manages to find a trap or animal before the intended victim, there is no penalty; it simply does not function. For example, if a friend finds a rubber snake in a victim's backpack and reveals it to the victim, the victim does not die, but the killer is still in the game.
In a capture elimination, a player eliminates his or her target by coming into possession of a specific item. Capture eliminations are exactly like tackles in flag football. Some common objects used as capture objectives are flags, articles of clothing, and clothespins. The winner will receive a substantial prize; worthy of not just a physical prize, but a title.
Some games set up a back story to explain why the players are trying to kill each other. Players may act as members of a league of assassins or part of an attack of vampires. Whether a theme is used is dependent upon the preferences of the individual who hosts the game.
In 2008, the University of Nebraska–Lincoln placed a one-year ban on the Assassin Game. The administrators of the school placed the ban after the police had been called by a person who observed one student bringing a NERF gun to class.
On March 31, 2009, in Fife, Washington, a Costco, several car dealerships and small businesses were evacuated when a "bomb" was left by someone playing Assassin. Several local police and fire departments responded as well as the Explosives Disposal team from the Port of Seattle, the FBI and the BATF. The bomb was a box "found in a flower bed, contained a magnet and a beeping motion sensor" with the words "bomb, you're dead" written on it. The "bomb" was defused. The man who left the package later turned himself in to authorities. 
On May 12, 2009, an incident involving the Assassin game happened behind a North Hampton, New Hampshire, restaurant, where an employee spotted a man in dark clothing with a gun. He called the police, and the student in question did not resist but simply walked to his car and explained the game to the police. The man turned out to be a high school senior from Exeter, New Hampshire, waiting for another high school student to come out of her job at the restaurant with a water pistol in hand.
- Salen and Zimmerman's Rules of Play.
- "Killer by Steve Jackson Games". 2007. Archived from the original on 20 February 2007. Retrieved 2007-02-18.
- Steve Jackson's Killer game (source: RPGnet)
- "U. of Nebraska Targets Assassin Game". 2008. Retrieved 2008-06-06.
- Lampe, Nelson (2008-02-21). "UNL calls dorm's 'Assassin' game inappropriate and bans it". The Boston Globe. Archived from the original on 17 May 2008. Retrieved 2008-04-23.
- "UTDallas can initiate disciplinary proceedings for students playing assassin 49.37(d)(24)". 2009. Retrieved 2009-09-21.
- "Man arrested in bomb prank that shut Fife businesses". 2009. Retrieved 2009-04-01.
- "Assassin game draws police response". 2009-05-12. Retrieved 2008-05-13.
- Assassins Guild Documentary directed by Gary Williams