Windows
XCOM: Enemy Unknown:
PC:
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.
Sid Meier's Civilization V:
PC:
OS: Windows® Vista SP2/ Windows® 7 
Processor: Intel Core 2 Duo 1.8 GHz or AMD Athlon X2 64 2.0 GHz 
Memory: 2GB RAM 
Graphics:256 MB ATI HD2600 XT or better, 256 MB nVidia 7900 GS or better, or Core i3 or better integrated graphics 
DirectX®: DirectX® version 9.0c 
Hard Drive: 8 GB Free 
Sound: DirectX 9.0c-compatible sound card 
Note: Optimized for the touch-screen Ultrabook™ device