"It works for me"

Very often, these days, this boils down to:
The game uses an anti cheat / anti piracy system which does support linux and proton, but the devs or management of the game decided against clicking a few boxes which would enable that support.
- Ey, the linux kernel is open source. Perhaps support can be added by some third party?
  But realistically, kernel level anti cheat doesn't really stop cheaters. But it grants third parties access to your pc's contents. Perhaps if more users switch to linux it might become a userbase worth marketing to. That is, if that's not users who run linux because they can't afford a windows license
  
  See my other post: Linux supporting ACs have existed for 3 years.
  The functionality to support them already exists, the market share is arguably already there, and the cost to game dev teams to enable these already existing linux AC functionality is in many cases literally 0. They're already paying to license Battleye or EAC or Denuvo, and all they have to do is request usage of a feature that already exists, that they are already paying for, but just not using.
  Also, as you seem to agree, the vast, vast majority of cheats/hacks/trainers are made for and used by Windows users despite ACs having kernel level access in Windows.
- Linux Copium, if it was like that go be Mr Hacker Man and toggle that undocumented switch so it works.
  
  I mean, its not undocumented.
  Easy Anti Cheat: https://www.gamingonlinux.com/2021/09/epic-games-announce-full-easy-anti-cheat-for-linux-including-wine-a-proton/
  Battleye: https://store.steampowered.com/news/group/4145017/view/3104663180636096966
  Denuvo: https://www.gamingonlinux.com/2021/01/steamworks-gets-denuvo-anti-cheat-heres-what-irdeto-say-about-linux-support/
  All of these common anti cheat developers have stated, 3 years ago, that their systems work on linux/proton, and that all a game dev team has to do is ask them to enable such functionality.
  Its just that the game devs/management, in many cases, do not do this.
  ...Even if one was capable of breaching a corporate network, compromising enough accounts or privilege escalating yourself to the point that you could remotely navigate through their intranet, build a version of the game, both server and client side, which supported linux/proton, test this, and then push it to release...
  Well for starters you would almost certainly be caught and go to jail for 10 to 20 years, and also this patch would immediately be undone once discovered.
  We're talking about online multiplayer games here.
  It's not a single player game where you can almost always find some kind of cracked version and run it offline in a VM or through Wine or something... and usually you don't even need to resort to cracks for single player games anyway as legitimately purchased games now mostly work fine via proton.
  Its when most of the game is reliant on a server architecture, you know, files not on your computer?
  
  I don't really wanna be the next pompompurin
- Because kernel level anti-cheat can be circumvented by modifying the kernel which Linux allows. -Kudos to the devs for not allowing cheaters. Also, these games have 'minimum spec' requirements where Linux is nowhere to be found on those specs. -They don't owe Linux users their support. And as you say 'Very often' - which implies there are still great games that simply don't work.
  Dual booting is a bother, and an overhead on storage as well as a main tech support issue for Linux users. Gaming in Linux isn't so straight forward either.
  
  The way popular anti cheats work on linux varies, and not much, afaik, is precisely known about them.
  Regardless of that... see my other post for 3 very widely used, very popular ACs which themselves state that they work on linux, have worked on linux for 3 years, that the support exists and all that has to be done is the game dev/management team to just say 'hey please enable this extra option for our game'.
  I say 'very often' because some games use their own proprietary, in house anti cheat which, yes, does not even claim to support linux.
  ...But the existence of major AC providers that do support linux means that it is not impossible to do this, in fact its been possible for years.
  Anyway, sure, none of this ultimately changes the fact that many of the most popular online games don't work on linux.
  But it also doesn't change that for many of such games, literally all they'd have to do is check some boxes, at either 0 or negligible increased cost to themselves, to make this work.
  Anyway, if you think most linux users are cheaters, I don't know what to tell you.
  Using linux to game is pretty easy, low barrier to entry. Steam Decks are basically ready to go right out of the box. Even desktop distros geared toward gaming on linux, but also work well as a general OS are not too difficult to set up. Nobara has come a long way, PopOS! is easier to set up than Windows.
  The technical know how to find and install a custom kernel is a much, much more complex task... and why would you even bother, when the vast majority of cheats/hacks/trainers are made for Windows, require far less technical know-how than setting up a custom linux kernel to use, and these routinely circumvent Anti Cheats all the time?

The trick is defining games you want to play as games that run on Linux.
- Been doing this for a bit, and it's worked out.
  At the very least it gives me an excuse to not play fortnite 🤢

It is really simple: I just don't want to play a game if it doesn't run on Linux.
No need to use bad software on my computer just to play a game :)
- Nah I don't actually game but use my computer for work and hobby :)
  
  What are some good games that don't run on linux? I just installed it on Saturday. And other than a couple tweaks to get Fallout 4 and 7 Days to Die to work right, I haven't found anything in my Steam library that doesn't work yet. Even some older stuff, like Commandos: Behind Enemy Lines. Just wondering what I'm going to miss out on.

I don't have time to play games anyway...

Losing Rust left a void in my life nothing has filled.
- You are free from your burden
- You have been cleansed
- We have Rust at home!

Plays every modern game I've thrown at it.
- Good for you! ProtonDB makes more sense than your anecdote.
  
  Are you just considering AAA slop that ships with anti-theft or "competitive" games?
  Also, Heroic Launch lets you pick Proton or vanilla Wine, so ProtonDB might list something as not compatible, but it works on Wine.