Except the first three that I have allready played through years ago and which are quite dated there is only the poor mans wing commander and a bad action game. Neither worth spending money or time with.
I do have an itch to play xcom apolypse though. But I still might have the cd somwhere unless it was scratched beyond recoginition. But nah Ill just play the new ufo. I just read another article from pelit magazine yesteryday about ufo extraterrestrial, that says that thanks to Bman and other mod makers the game is now a classic and worthy heir of the ufo series.