The biggest one I miss, and it works, but the anti-cheat keeps me from my favorite servers is anything from the Red Orchestra series. I really enjoy their newer game Rising Storm 2 but the vast majority of the servers are protected with an anti-cheat that keeps me from joining. I’ve found a couple servers that don’t use the anti-cheat and I can play on those, but they’re not quite the same as some of the servers I have as favorites that are playable on Windows. Otherwise, most things generally work good, biggest problem is with launchers, and even those can be bypassed or fixed, but I’ve gotten to the point in my life where I just want things to work without having to remember what config files I’ve changed or futz with that may break in the future. The other games that I’ve had that don’t work may as well now, but honestly I’ve forgotten what they were. One that I don’t play, that I know a lot of people do is Destiny and I saw that they’ll ban you if you try on Linux. But I’ve only heard that as I haven’t played that on PC.