minimal:
reqprocessor: i5 2.0 ghz+
reqgraphics: GeForce GTX 460 / ATI Radeon 6850 / Intel HD 5000+
reqmemory: 5 GB RAM
reqdiskspace: 5 GB available space
reqsystem: Ubuntu 12.04+ 64-bit, SteamOS+
reqother: Other Linux distro should work but haven't been tested.

recommended:
reqprocessor: i5 2.5 ghz+
reqgraphics: GeForce GTX 660 / ATI Radeon 7850
reqmemory: 6 GB RAM
reqdiskspace: 5 GB available space
reqsystem: Ubuntu 12.04+ 64-bit, SteamOS+
reqother: Other Linux distro should work but haven't been tested