Xenonauts is a spiritual successor to the original
X-Com. A very good successor as well. It keeps to the 2D, isometric style of the game, but improves on the fun parts of it as well and removes the not so fun parts. If you've never played the new or original
X-Com, it's a turn based strategy game set on defeating aliens on semi-random maps, but be warned, it's still 2D and I'm sure that is a no go for some gamers.