Counter-Strike is the original version of the #1 online action game in the world. Counter-Strike: Condition Zero (CS:CZ) advances this award-winning series by introducing three single-player gaming modes and extending the award-winning multiplayer experience. In the Tour of Duty campaign, players are challenged to complete over a dozen tactical missions. As they progress, new items and squad mates are made available to them. The official CS bot allows players to simulate multiplayer games offline with bots or online with a combination of bots and human players.