Isn't Proxmox intended for servers whose only use is to run VMs? Why not go for a traditional desktop distro like Mint and run KVM, QEMU, or VirtualBox on it?

Anyway, I have heard something like this, but it probably depends on the anti-cheat. Some might run in kernel mode to deliberately detect VMs. Others won't care if you use a VM.

All depends on the games you play, personally is mostly emulators and indie so there's no problem. Generally the more online/micro transactions, the more hostile the game will be to vms

If you want a list just google what games can be played in a qemu vm

Can't speak to anti-cheat, but I've run a Windows 11 VM with GPU passthrough on Proxmox. I got basically identical performance from the hardware, considering the reduced ram/cpu count in the VM. USB port passthrough was glitchy though. I didn't spend too much time messing with it but it definitely was functional. Battlenet (World of Warcraft, Overwatch, etc...) worked fine. I don't recall any game that didn't run but, again, I didn't do too much.

I use Steam + Proton in an LXC so I can share the graphics card among several other containers. It works quite well with streaming once I got it set up.

Surprised that nobody yelled Proton yet? Lots of Windows games running pretty good, some close to native, some even better on Linux through Proton. But here is the thing you mentioned which could be a problem: anti cheat. It works on Linux but depends on the developer to enable it. Some major games simply does not support it. You can check them here: https://areweanticheatyet.com/ , for general compability check https://protondb.com , even non Steam games can run through Lutris with little to no hassle. Proxmox with GPU passthrough seems like a big clunky overhead in terms of gaming but maybe you got that game that will never run on Linux.

I'm in the planning stages of a build that will be essentially this, a proxmox build that'll include my NAS with several hard drives (running in one VM), all my docker containers (another VM) and Linux and Windows vms with passthrough that I can spin up temporarily for games.

I think I can get the Windows VM in a place where I can also restart the whole machine and boot in natively, as a fallback for games with aggressive anti cheats that won't allow VMs, which I don't think I'll be playing much of anyway.

To answer your question, it really would be best to check game by game if the anti cheat allows VMs.

Yea its doable. Really depends on the games anti-cheat. You'd want to check each game.

Battle Eye based anti cheat games like R6S and Tarkov gave me issues last time i tried a similar setup. That was a few years back however, and with valves proton push, much of the compatibility has improved since then.

It's feasible. I ran that so setup for a couple of years. Not with Proxmox as desktop system, but Windows VM with VGA passthrough for gaming, relying on Steam in-home streaming.
Wouldn't recommend. I didn't find a ton of games that wouldn't work, but the performance hit was quite noticeable in hindsight.
I never sorted out core-pinning, though.
But overall the setup was very fragile and prone to breaking after random updates just as much as randomly fixing itself with the next update.
Streaming was probably the biggest pain point, though.

I don't think Proxmox is supposed to be a daily driver, but I think this would work, except for maybe Anti-Cheat as you mentioned.

Video card passthrough can be a real struggle. If you are using Intel/Nvidia it will be easier though

I have proxmox running on a nuc and do a GPU passthrough to a windows VM. I haven't encountered any anti cheat issues yet, but I honestly don't game near as much as I used to.

Marauders is the only game that I have had an issue with. I'm not a prolific gamer but everything else I have tried has been fine.