Counter-Strike: Condition Zero (abbreviated CS: CZ or just CZ) is the newer version of the multiplayer game, Counter-Strike. The game was released in 2004 using the GoldSrc Half-Life engine. CS: CZ features a multiplayer mode, which mostly features updated character models, textures, maps and other graphical tweaks. Unlike other Counter-Strike games, Condition Zero also contains a single player mission pack with the player unlocking maps and more efficient bots as they pass certain requirements for each map while playing as a counter terrorist. These requirements include targets such as, "Kill 3 enemies with a glock" or "Win a round in 45 seconds." Condition Zero also contains bots with better AI than other Counter-Strike games.

As of 2008, the game is one of the ten most played Half-Life modifications in terms of players, according to GameSpy.