Mischief Maker wrote:

Motherfuck UFO: Extraterrestrials!

This is an excellent Freeware OpenSource X-Com alike. It has everything: Base management, research, Geoscape, turn-based tactical combat. Plus what little I have seen of the production values are way less comicbook/anime gay than the original X-Com.

On the downside, it uses the Quake 2 engine so get ready for some seriously blocky models and it's still suffering from a couple bugs and a few missing graphics in the info screens. The biggest problem is that the game currently has no manual and a minimal tutorial so get ready to spend some quality time with the Wiki. ALso it's a Sourceforge DL so you need to download all the files individually instead of one big installer (or am I wrong? Could someone clarify on that?)