I have recently bought the game on gog, but I have played XCom and friends since the first version 25 years ago. In the recent-ish years I was following the UFO:AI project, which is a very nice open source take on the subject. All this to say that one of its strong points is the very deep research tree that ties in with the lore. During the first playthroughs you really try to pace up the research because you are left wanting for more. This could be something to look at in this respect.