Now recently 2k came out with their own "rehash" of X-Com. That was not so much a X-com game as a heavily inspired and scripted evolution of the original. Xenonauts follows the original formula to a T, and adds it's own enhancements. It was also done by a small indie group, and had backer and community support and suggestions added into it. (It also supports modding, and has a variety of mods available to it, as well as the ability to modify various parameters in your own game).
Here are some quick comparisons between the original game and Xenonauts, in picture form. Then it's to the youtube section of this blog post!