Instagib
Instagib is a term derived from Unreal Tournament, a famous Epic title. In instagib, the maximum amount of health a player can have is limited to one and thus players are able to kill each other with no more than a single shot or special move. It is usually battle that is played this way, although one can host any other game type should he wish to. Levels specially designed for instagib are usually very small and players often claim that such a game mode is too chaotic and virtually requires no skill.
Many programs allowing this custom game mode to be played have been released but now it’s JJ2+ that is used the most.