A Live Action Role-Playing Game (often abbreviated LARP), is one in which the events of the game are acted out, instead of being described and decided by dice rolls. As such it is similar to children's "make belief" games, though more structured.
LARPs are usually played in the form of conventions, or "Cons". These are pre-planned dates where players gather for a game. They can range from a handful of players to several hundred, and from a few hours of time to several days. Typical sizes are 50 to 100 players and 2-3 days, where the first and last day are also used for travel, so the game often starts in the evening of the first day and ends at noon of the last.
Cons are usually organized by an organisational team. Aside from the players, there are also non-player characters ("NPCs") which are played by people who enjoy this aspect of LARP. See below for more details.
The organisational team will usually create a storyline, brief the NPCs and prepare the game area. They also act as game-masters or referees throughout the game to answer any rules questions, settle any disputes and resolve the effects of player actions on the storyline.
Cons usually delimit "in time" and "out time" very clearly, typically with an explicit announcement by the organisational team or game-masters. During "in time", players are expect to act as their characters only, while "out time" the character play is suspended and players are free to, for example, discuss their real lifes. Commonly, a LARP event consists of only one period of "in time", which can then last for several days, and includes the nights. Play often continues, though at reduced intensity, throughout the sleeping hours. Less commonly, play is interrupted during the night with "out time" periods for sleeping.
Aside from organising one, there are two ways to participate in a LARP con: As a player, or as a non-player character.
Player characters are very similar to those in pen and paper RPGs. They are created according to the game rules, and one player will play one character throughout the entire time of the event. Characters also progress, receiving experience points with which they can acquire new skills, talents, magic spells and so forth.
Non-player characters, on the other hand, are people who do not play their own characters, but those provided by the game-masters. These are either plot characters, who stay constant throughout the event and are important to the storyline, such as the nemesis, evil overlord, or just the janitor of the castle. In addition to these, there are also a large number of unimportant NPCs, especially for combat scenes. These are the soldiers, orcs, undead or other enemies of the players who appear in large numbers.
NPC roles are usually available at a reduced cost. In addition, many people enjoy playing without being tied to one character, being able to experience different roles throughout the game, or simply being able to play the combat part of the game without having to watch out for (played) injury and death.
In LARP games, people will often act out combat scenarios using replicas of weapons (usually made out of wood or foam rubber).
Like other games, a Live Action RPG has rules. As they need to be remembered and applied during physical action, they are often very simple compared to pen and paper role-playing games. For example, in many LARP rules, all hits during combat do 1 point of damage, no matter what kind of weapon was used or where, how well or how hard the hit was.
One extreme of the spectrum are LARP events at which the rule is that you can do whatever you can do, or as a slight variation, that you can do whatever you can convincingly play. The other extreme includes rules with detailed systems for character creation, task resolution and others, very similar to pen and paper RPGs, except that dice are replaced by either a non-random resolution mechanism, or one more suitable for moving around probably in the forest, such as drawing coloured marbles from an opaque purse.
Most rules systems fall inbetween. Commonly, rules systems for character creation and character progress are more complicated (since these steps can be done at leisure and with pen and paper) than those used during the action phases of the game. Combat rules are almost always very simplified due to the necessary speed and unambiguousness of task resolution.
LARP players are typically very conscious of safety, as the sometimes rapid action, and during many events the gameplay during the early morning, late evening, or even the night hours, can lead to dangerous situations.
All weapons used during LARP events are specially crafted soft weapons that consist of latex, foam and other soft materials. They are also typically checked for safety by the organisational team before being allowed into the game.
There is also always a "safe word" agreed on, commonly "Stop" or "Hold", with the rule being that it is used in situations of real (not played) danger. Upon hearing the "Stop" command, all play action has to cease immediately, with everyone freezing whatever he or she may be doing at that time, until the danger has been identified and resolved.
In addition, LARP etiquette makes it a point to address safety and responsibility. For example, it is a typical rule that whoever causes an injury to someone else, no matter how small or accidental, is responsible to ensure that the injured player is taken care of.