sv_cheats
sv_cheats is a console variable available in all 
Source games.
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This boolean cvar enables/disables cheats on the server. Enabling this will disable Steam Achievements in some games..
It also gives you access to commmands that would normally be abused or misused by players. When building maps, you may want this as a startup command.
Syntax: sv_cheats <boolean>
Note:In 
The Stanley Parable (excluding the Demo), this command will briefly turn on and off, then send the user to "The Serious Room", ending their save game. This can be bypassed by replacing the bin\client.dll from the paid version with the demo one.Note:Enabling cheats in 
Hunt Down the Freeman will give the player an achievement.
Important:In older version of 
GoldSrc, prior to an update, a map restart or changelevel is required in order to fully enable Cheats.See Also
Below are some typical cheats which gamers may find useful. Developers may also find these useful for bug testings and specific testing on in-game worlds.
god- "God Mode": Player becomes invincible. Type again to turn off.impulse 101- Equip the player with a full loadout of equipment, or gives player max money amount ($16000) in all Counter-Strike games.impulse 203- Remove an entity.give <entity name>- Give the player the item, weapon, entity or asset stated.noclip- Toggle the player collision with the environment and other objects. Allows the player to fly through walls, etc. Type again to turn off.notarget- Toggle NPC detection of the player. The player will still activate trigger entities, etc. Type again to turn off.
