Console commands

The Console is a feature of many games that can be used to change certain elements of a game. In Left 4 Dead, it can be activated in the Options menu and then displayed by pressing the tilde (~) key in game. Valve features a quick-type feature in their consoles that allow rapid entry of commands.

'sv_cheats'
The 'sv_cheats' is a prerequisite command to many of the game-altering commands found in Left 4 Dead. By setting sv_cheats to 1, most all commands are then recognized by the game. It is with 'sv_cheats 1' that most of the exploits found by users in the demo during its pre-order era.

Complete List of Commands
For reference, a complete list (21 pages) of console commands canbe found here:.