The chaos that has overtaken the city means a brutal battle for survival. Every squad member must bring their specialist skills to the fight to ensure the mission succeeds.系统需求Minimum: OS *:Windows Vista(R)/XP, Windows 7 Processor:Intel(R) Core(TM)2 Duo 2.4 Ghz or better, AMD Athlon(TM) X2 2.8 Ghz or better Memory:2 GB RAM Graphics:NVIDIA(R) GeForce(R) 8800GTS or better, ATI Radeon(TM) HD 3850 or better DirectX®:9.0c Hard Drive:8 GB HD space Sound:Standard audio device Other Requirements:Broadband Internet connection Additional:Internet connection required for game activation. To play online, activate an online account using a product key. Limit one account per key. 1 product key included. Game not playable until release date. Games for Windows–LIVE System Requirements: Multiplayer play and other LIVE features included at no charge; games may offer additional downloads that may require additional fees. LIVE is not available in all countries, visit for more information. Features and system requirements may change without notice. Subject to Terms of Use (at . Broadband Internet service required (sold separately). Some broadband services may not work with LIVE and performance may vary. Under 13 requires parental consent. See for full details. Recommended: OS *:Windows Vista(R)/XP, Windows 7 Processor:Intel(R) Core(TM)2 Quad 2.7 Ghz or better, AMD Phenom(TM)II X4 3 Ghz or better Memory:4 GB RAM Graphics:NVIDIA(R) GeForce(R) GTX 560 or better DirectX®:9.0c Hard Drive:8 GB HD space Sound:Standard audio device Other Requirements:Broadband Internet connection Additional:Internet connection required for game activation. To play online, activate an online account using a product key. Limit one account per key. 1 product key included. Game not playable until release date. Games for Windows–LIVE System Requirements: Multiplayer play and other LIVE features included at no charge; games may offer additional downloads that may require additional fees. LIVE is not available in all countries, visit for more information. Features and system requirements may change without notice. Subject to Terms of Use (at . Broadband Internet service required (sold separately). Some broadband services may not work with LIVE and performance may vary. Under 13 requires parental consent. See for full details. *2024 年 1 月 1 日（PT）起，Steam 客户端将仅支持 Windows 10 及更新版本。