The sv_cheats console variable is a prerequisite command to many of the game-altering commands found in the Left 4 Dead series (including other Valve games, such as Half-Life). In the Left 4 Dead series, by setting sv_cheats to 1, most commands are then recognized by the game. It is with sv_cheats 1 that most of the exploits were found by users in the demo during its pre-order era.