: Often provides discounted Steam keys, with recent prices as low as $9.99 $5.39 (46% off). Humble Store : Sells the Steam version for $9.99 . Minimum System Requirements for PC

: Offers a DRM-free version of the Complete Pack, which is often recommended by users over the Steam version due to simpler license terms.

: NVIDIA GeForce 8600 GT / ATI Radeon HD 2600 XT or better Storage : 20 GB available space XCOM: Enemy Within on Steam

According to Steam and Humble Bundle , you will need at least: : Windows Vista or Windows 7 Processor : 2 GHz Dual Core Memory : 2 GB RAM