A growing collection of computer games that are freeware, open source or free to play.

UFO: ALIEN INVASION is a strategy game featuring tactical combat against hostile alien forces which are about to infiltrate earth at this very moment. You are in command of a small special unit which has been founded to face the alien strike force. To be successful on the long run, you will also have to have a research team study the aliens and their technologies in order to learn as much as possible about their technology, their goals and the aliens themselves.

The game is inspired by the ‘X-COM’ series by Mythos and Microprose. Another similar game would be the Jagged Alliance series.

The game is turn-based. Each member of your squad has a limited number so called “time units” each round, which are consumed when you order the unit to walk, to fire a weapon or to perform any of the other miscellaneous actions. When all your forces are out of time units, the alien’s turn starts. In addition to eliminating as many enemies as possible, your mission is to minimize civilian casualties as well as to acquire parts of the advanced alien technology.
Once you’ve acquired sufficient samples of the unknown technology, your research labs will be able to reproduce the alien weapons and devices in order to use them against their original creators.