Counter-Strike: Condition Zero has been officially announced by Valve on Steam for Linux, making it the fifth little from their collection to reach the open source platform.
Counter-Strike: Condition Zero features an extensive Tour of Duty campaign, a near-limitless number of skirmish modes, updates and new content for Counter-Strike's multiplayer game play, not to mention over 12 bonus single-player missions.
It can be bought as a stand-alone package, along with the original Counter-Strike, but it's also available in other collections such as Counter-Strike 1 Anthology (Counter-Strike, Day of Defeat, Deathmatch Classic, Ricochet, Counter-Strike: Condition Zero), and Counter-Strike Complete (Counter-Strike, Counter-Strike: Condition Zero, Counter-Strike: Source, Counter-Strike: Global Offensive).
The system requirements are quite low and most of the computers in use today will be able to run it without any problems.
More details about this title can be found on the official Steam website