Re: Linux gaming: Sorry, I couldn't hear you over the sound of the MCC playing on my Linux box. And Ori. And Stardew, RoR2, Everspace, XCOM2, SWTOR, Hades, DST, Hollow Knight, FTL, Terraria, Human Fall Flat, Portal 1/2, and a variety of other games.
As far as anticheat is concerned, that's actively being worked on by Valve and the largest stake holders.
But to the working games, let me add: Overwatch, League of Legends, Anything from GBA/GB/NES/SNES/DS/OtherRetroSystems, Starcraft. Oh, and Minecraft of course.
I'm sure I can come up with more.
Edit: One steam library checking later - and I'll note, this is stuff that I've actually played on Linux (and is also filtered by names I think people would recognize): Arma 3, Blitzkrieg 2, Pit People, Castle Crashers, BattleBlock Theater, Unturned, Invisible Inc., Baldurs Gate, Undertale, Speedrunners, Dota 2, Gary's Mod, Everspace, Raft, AoE 3.
This makes up the VAST majority of my steam library, none of which was purchased checking for Linux compatibility.
It's one thing to say that a specific game you want doesn't work, and quite another to say it in general doesn't work.
Edit again: Rocket League. That's it. That's the only one that I know of issues with, and I don't know if it even still has issues - I stopped playing when it required an Epic account.
Oh hey, lookie there: https://www.protondb.com/app/252950 . Sounds like that works too.