Wintermute
Augur
X-COM: Enemy Unknown (1994)
It's X-COM: UFO Defense (or UFO: Enemy Unknown, in Europe). But at least you didn't call it XCOM.
Another frustrating aspect were the alien leaders and commanders - which you have to capture later on as part of the endgame. I never could figure out how to tell them apart from regular soldiers.
Use a mind probe.
I never got to experience an alien retaliation
Unlike other games, the aliens are actually playing the game here. They must find your base before they can attack it. If you shoot down all the scouts on retaliation missions, base invasions won't happen.