My favorite X-Com remake was UFO Aftermath, except for its buggy game engine. I would suggest that you add the Transgenants (zombified animals and humans) from AM, as well as Robotic Invaders. Also, it would be a great idea to put real weapons into the game (M16s, MP5s, Glocks, etc.) like in Aftermath. I would like you to at least consider these ideas.
P.S. This is the same name as my profile on ModDB