Counter-Strike: Condition Zero is a first-person shooting game developed by Rogue Entertainment, Gearbox Software, Ritual Entertainment, and Turtle Rock Studios under Valve Corporation's management for Microsoft Windows and Mac OS. It is a follow-up to the Half-Life mod, Counter-Strike and features a multiplayer mode and single-player mission pack.
Originally worked on by Ritual Entertainment, the project due to quality issues and their share of work was overtaken by Gearbox Software. Unfortunately, development delays lead to the work being handed off to Ritual Entertainment. Ritual completed the game, but when review copies lead to a low average grade, the game was handed off and reworked by Turtle Rock Studios.