Me and some other guys are making a remake of the first original x-com game, though with some modifications. For example, you can now play multiplayer 1 vs 1, aliens vs x-com with all the good parts included, such as base building and researching. We are currently updating the graphics as well.
Check out our project at http://ufotts.ninex.info/
There is a demo you can try but it´s pretty outdated. We will soon release a new version which is much more stable and fun to play.