There are dozens of fully flushed out Xcom and Bullet Hell/Shmup combat systems as assets accross the unity and unreal webstores. They demo'd combat in this form as prerelease footage and marketing material before true "work" on the game even started. So like their ingame enemies said in such a lolsorandom 4th wall fashion, everything but the FOW models is prebought stuff they're cobbling together into a game.
If they didn't, they should have. Might have cut down on the 2 years of devhell before being forced to release to keep the lights on. If their extra special 12 man teams coders did all this inhouse, it's pretty shit and looks exactly like they stripped down something from the assetstore into the most barebones of space/ground combat system.
Only design philosophy on display is "It's a porngame, who cares about combat progression" with the zero difficulty, pointless upgrades, and completely broken clear rating system. If it isn't a prebought asset Why is there a clear rating at all. It isn't tracked anywhere, it has no bearing on payout of money or PP points, and planets aren't repeatable. Occam's razor, it's present in the prebought assets and no one connected it to the larger game design. It's just hanging there as a vestigial limb giving you Gold while clearing ground combat despite losing several characters or bronze in every random ship combat. You wouldn't code this in, you'd just put a "Success" rubber stamp at the end of levels, if you weren't working with someone elses assets. Which is worse, gross incompetence or asset flipping? Considering this is the "strong" part of the game.
They get zero points for what someone else made before the game was a twinkle in FOWs eye working as intended, but lose a lot that it doesn't.