From LQWiki
UFO: Alien Invasion is an turn based strategy game inspired on the famous X-COM series. Unlike the original X-COM this game is relays on a heavily modified version of ID's Quake 2 engine.
The player must lead a special task force through different scenarios in a search and destroy mission to get rid of invading alien forces.
Although still beta the game is already fully playable and quite addictive. Both Techical Demo1 and the Special Christmas Demopack includes scenarios were you can test everything which is already implemented. New features are being included on popular demand (watch the user forum). The second Tech-Demo should be ready during the first quarter of 2005 and will surely include new alien races, weapons and features. The game permits networked games, although there are no official servers running.
Install
Tech Demo 1 is a tarball (*.tar.bz2), while the Christmas special demopack is available via bittorrent. Once downloaded unpack it, copy the directory to where you want it to live. That's all. The binary is invoked from within this directory. You can also compile it yourself if you want to. Gentoo users will want to emerge it in the standard way: emerge -Dav ufo-ai
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