With its extensive Tour of Duty campaign, a near-limitless number of skirmish modes, updates and new content for Counter-Strike's award-winning multiplayer game play, plus over 12 bonus single player missions, Counter-Strike: Condition Zero is a tremendous offering of single and multiplayer content. The game was released in 2004 using the GoldSrc Half-Life engine. CS:CZ features a multiplayer mode, which features updated character models, textures, maps and other graphical tweaks. Unlike other Counter-Strike games, Condition Zero also contains a single-player mission pack with the player playing as counter-terrorist alongside bots. The player unlocks maps and more effective bot teammates as he or she passes certain requirements for each map while playing as a counter terrorist. These requirements include targets such as "kill 3 enemies with a Bullpup" or "win a round in 60 seconds". Counter-Strike bots are a prominent part of Condition Zero gameplay.