Counter-Strike: Condition Zero advances the #1 online action game series by introducing objective based single-player action, the official CS bot, and special enhancements for online play. CS:CZ is a tactical action game that challenges you to compete with and against cunning computerized opponents in a Tour of Duty across the globe.
This is excellent. It has all that is good about original Counter-Strike, but also includes bots of various skill levels to play offline against, as well as a series of Campaign-style games with bots where various objectives are to be met.