UFO: Alien Invasion

UFO: Alien Invasion is a strategy video game in which the player fights aliens that are trying to take control of the Earth. The game is heavily influenced by the X-COM series (mostly by UFO: Enemy Unknown). It is based on a modified id Tech 2 engine, and runs on Linux, FreeBSD, Microsoft Windows, AmigaOS 4, and Mac OS X for both PPC and Intel Macs. There is also a version for Android, published on Android Market.