counter-strike condition zero

Counter-Strike: Condition Zero is a first-person shooter video game developed by Ritual Entertainment, Turtle Rock Studios, and Valve, and published by Sierra Entertainment and Valve. The follow-up to Counter-Strike (2000), it was released in March 2004 for Windows. Condition Zero utilizes the GoldSrc engine and has a multiplayer mode, which features updated character models, textures, maps and other graphical tweaks. It also includes two single-player campaigns; Tour of Duty and Condition Zero: Deleted Scenes.
Alongside various other Valve titles, the game received versions for OS X and Linux in 2013.