XCOM UFO Defense: Walkthrough/Strategy Guide - Steam Community
: Visit the OpenXcom website and download the latest "Nightly" or "Extended" version for Windows.
: You can buy X-COM: UFO Defense at the Steam Store for approximately $4.99.
OpenXcom is a community-driven open-source clone that fixes game-breaking bugs (like the difficulty reset bug) and adds modern features like high resolution and scaling.
: The GOG.com version often costs around $5.99 and is DRM-free, making it very easy to move files.