Oh my, this was literally TFTD for me! It was my first ever X-Com game (I was surprised it’s based in the oceans, I didn’t know about UFO: Enemy Unknown), and I absolutely knew nothing about it, how it’s difficult even on the easiest level that I played. Mind you I also played this on an old black-and-white monitor (I live in Eastern Europe, my family was a bit poor, we had no Internet, and this was in year 2000, I was only 14), and not very bright, so you can only imagine the night missions… Especially the alien colony missions were a real pain in the ***. All this made me so much frustrated with the game during my first try, I was always constantly on the edge of defeat (and was defeated at least once) – but I somehow managed to finish it. I just HAD to keep it going, the mystery was too enticing. And I was especially satisfied when I finally discovered the origins of these aliens and their aims, plus much of their autopsies (and yeah, I fell for the tech bug I didn’t know about too). This is how original X-Com games are addicting During the first game the mystery just hooks you in, trying to solve it to the end.

I’d also argue that the way alien types are phased out is heavy-handed. By the endgame, it feels like all you fight are mutons and sectopods. I’d like to see the weaker aliens stay in the mix, and all aliens get new abilities (perhaps unlocked after the base; “the aliens have changed their tactics!”) to make them more synergistic.

Actually, I think arming the aliens with bigger guns might even work for your scenario. Fail a mission and the aliens are better armed in future, but if you win later on you get to steal those high-tech weapons for yourself. Hopefully it could be balanced so that it would be slower than researching them optimally, but still provide a balancing factor that could potentially right things for the player somewhat.

Crusader Kings 2 is another game that uses AI to be simple yet believable: every character has obvious reason to like or hate every other but has secret plots and desires. Not so varied and personal yet very engaging. And XCOM… It doesn’t need much of AI. Tactical AI is good as it is (and anyway all the challenge is in fighting giant armored psychic snipers who can kill you with their spit, they don’t need to be very smart), and strategic AI could be very basic.

For example, the AI I hate most in Civ V is Egypt. Ramses actually seems to be very proactive about utilizing his advantages. He goes chariot-heavy early on and goes on a rampage, but also uses his ever-expanding empire to found a religion (typically production-focused) and build some wonders. By the mid-game he’s either been beaten by me or steamrolled over virtually everyone else in his path and shifted into a more cultural playstyle. If I don’t take care of him early on, or if he’s on another continent, he will always, ALWAYS be a superpower who eclipses everyone else in score, military might, territory (if he’s on another continent, it will almost invariably be entirely his by the time I get there), and production (which he uses to steal wonders at every turn), meaning that the only real option is to go for a science or cultural victory, and he’s very hard to beat at either of those. The difference between his pre-expansion and post-expansion game are mind-boggling.

The XCOM team need to talk to the Civ V team about AI, because I think they’ve finally figured it out well enough to do some good here.

Past that, how can you avoid a potential negative feedback loop if you allow the aliens meaningful actions within the game? Your argument–which I again agree with–was that the aliens don’t really do anything, but if they did something then the player would always be in a position where consistent failure to stop them would result in a negative feedback loop. If not, then they aren’t really doing anything, are they? Oh, and the game already has a potential negative feedback loop: fail to protect enough nations and your terror ratings go up which causes nations to leave so you don’t have enough funds to adequately protect the remaining ones and on and on until game over. Negative feedback loops are fine in strategy games. That’s why you have to have a strategy!

I’m not saying that the game would have to immediately start with something drastic. As is, the game already has a progression of ship types, but currently it’s not very meaningful. They are bigger, harder to shoot down, and more dangerous/tedious to get through, but they have so little impact I don’t even know what the different varieties are called. My idea was basically to very gradually sprinkle in a single tougher version of each type of alien (not wholesale replace the existing ones; something sort of like Skyrim’s leveled enemy system, but based on the player’s failure to stop the aliens), with good players being able to delay that for most of the campaign, while simultaneously offering a science-based, risk v. reward system back at base to keep that from being so much like an assembly line. Regardless of whether its a good idea or not, I think the game desperately needs some improvements to both the campaign and the base-building side of things to keep it from being a tedious, identical march towards victory every time.

A potential problem with your idea is that it’s a negative feedback loop. Failing to stop a harvesting ship crewed by regular sectoids results in them becoming super-sectoids who will slaughter your men even more handily, and you end up with a failed campaign because you simply can’t make any headway. I personally would go for introducing new aliens at given time milestones (NOT progression milestones) with a small error factor each way; that way you can alter the timing of their introduction to the game in response to the expected skill level of the player as indicated by the difficulty level they’ve picked. It would be nice to have something a little more reactive, as in your example, but the problem with a complex system like that is that they’re immensely tricky to get working correctly and consistently.