The developers of the open source (meaning it's going to be free) game UFO: Alien Invasion have announced that it will take them some more time before they can release their second techdemo, but to make up for this they have released a christmas special - a stand alone version of their first techdemo, this time featuring more maps than the original demo, all of them never seen before, new weapons and a few other goodies.
No map in this pack has been released before, so if you like this kind of games, you might want both the
christmas special, and the
original demo which is hosted by gamershell.com.
Both demos are available for windows and linux. The minimum system requirements are a 333+MHz processor and an openGL compatible Graphics Card - if you don't know what that means: if Quake3 runs on your PC, that will easily do.
You can find out more at the homepage of the ufo:ai team,
http://ufoai.net

(click to enlarge)
UFO: Alien Invasion is a fanmade project, similar to
Project Xenocide, which is inspired by Mythos Games' (R.I.P.) X-Com Series. In short you have to combat aliens in both turn based combat, and realtime world-scale strategy, altough the current techdemo features turnbased combat only. A second techdemo, which will put the first techdemo and the christmas special to shame, is currently worked at, but it will likely take a few more months before it is going to be released.
The game itself is based on a heavily modified quake 2 engine, which despite it's age is still much better than what your usual free game has to offer.