CZ

Counter-Strike: Condition Zero (abbreviated CS: CZ or just CZ) is the single player version of the multiplayer game, Counter-Strike. The game was released in 2004 using the GoldSrc Half-Life engine. CS: CZ also features a multiplayer mode, which mostly features updated character models, textures, maps and other graphical tweaks.

It is very similar to Counter-Strike 1.6, featuring nearly identical gameplay, weapons, equipment, and maps popular in the multiplayer version. The textures are all different, as are the guns and maps. Nightvision makes a whirring, whining noise and in some servers casts an eerie glow around the player when in use. Also, players drop their grenades when they die, allowing other players to take them. CZ offers a new bot system in which the player can "create" computer players of varying skill levels and control the weapons they use to practice. In the single-player campaign, the player leads a hand-picked squad of counter-terrorists through missions around the world thwarting terrorists. The single-player mode is often praised for the highly intelligent AI, which are made to emulate actual players.

(from wikipedia.com)