You almost have to go out of your way to make a game incompatible with linux. Considering wine/proton and their various forks cover the vast majority of things at this point.
Even with ACs, the two most used ones completely support Linux. One is completely out of the box, maybe even as far as linux support being opt out. The other requires you to contact its developers to enable compatibility their end iirc.
I don't agree. There are cases with Windows only root kits for DRM, but there are also games that don't work because of bugs. You see games coming out that barely work on Windows.
Yeah, there's this very obscure match-3 game I wanted to play because of nostalgia. The series peaked with 3 and 4 (and those are the ones we played on the family computer circa 2015) and worked perfectly on Windows. Now 3 works perfectly (in terms of compatibility) but 4 was better (in terms of gameplay). 4 is marked as borked, last I checked. For anyone wondering, it's The Treasures of Montezuma series.