Sadly there was one aspect present in the first ufo:enemy unknown and mostly absent from all others versions, sequels, reboots, etc : it's the mystery and dread of "first encounter".
On the original game, I was roleplaying a lot - letting the aliens fire the first shot in the 1st mission. I loved the "what do they want" mystery, and the scientific investigations on the aliens are still my favorite part. I like the "invasion" project to be slowly revealed, and the "ufology" aspect to be stressed out by the difference of technology.
So, these Aftershock, etc, games don't interest me much : they are just humans-versus-aliens tactical games, and I already have Starcraft or whatnot about this. The recent xcom games (both the tactical one and the 3rd person shooter) look like they immediately equip you with futuristic scifi material, making it too early some space age war thing. And xenonauts, while the most faithful so far, starts with earth surrounded with flying saucers - there goes the elusive "shadow war" feeling of the first game.
So, beyond all their pros and cons, gameplay-wise, I regret that the one thing I loved most about about the original game (that kind of traditional men-in-black investigation and response to an occult threat) is absent from all the games inspired by it. They all kinda miss the flavor point that was making its appeal to me.
Enough ranting, back to
ufo. Still many episodes ahead...