XCOM: Enemy Unknown + XCOM Enemy Within Bundle PC Steam CD Key

Windows

OS:Windows Vista
Processor:2 GHz Dual Core
Memory:2 GB RAM
Graphics:NVIDIA GeForce 8600 GT / ATI Radeon HD 2600 XT or greater
DirectX®:9.0
Hard Drive:20 GB HD space
Sound:DirectX Compatible
Other Requirements:Broadband Internet connection
Additional:Initial installation requires one-time internet connection for Steam authentication; software installations required (included with the game) include Steam Client, Visual C++ 2008 Redistributable, DirectX and Microsoft .NET 4. 

Mac

OS: 10.8.5 (Mountain Lion)
Processor: 2.0 GHz Intel Core 2 Duo (Dual-Core)
Memory: 4 GB RAM
Hard Disk Space: 20 GB
Video Memory: 256 MB
Video Card: AMD HD4000 / NVIDIA 9000 Series (See NOTICE for details)
Additional: Broadband Internet Connection.
NOTICE:The following graphics cards are not supported: ATI X1xxx series, ATI HD2xxx series, Intel GMA series, NVIDIA 7xxx series, NVIDIA 8xxx series. The following cards require you to have 8GB of system RAM: NVIDIA 320M, NVIDIA 9400 and Intel HD3000. 

Linux

OS: Ubuntu 14.04 (64 bit required)
Processor: 2GHz
Memory: 4GB Memory
Graphics: 512MB*
Hard Drive:16GB HD space
Other Requirements: Nvidia 600 series+, AMD 6000 series+, Intel Iris Pro.
IMPORTANT: Requires 64bit OS to play.