Anti-cheat software

Anti-cheat software is software designed prevent cheating in videogames. Typically, client-side anticheat prevents games from running on Linux.

VAC (created by Valve) natively supports Linux. Moreover, the anticheats EasyAntiCheat and BattleEye currently have support for Linux through Proton. This has resulted in some games enabling this Linux support. You can see which games have done so here.

EasyAntiCheat

EasyAntiCheat became supported in a recent Epic Games EasyAntiCheat SDK. Since many EasyAntiCheat games don't use this SDK, many games must update or change out their anticheat SDK to be able enable Proton support.

BattleEye

Developers can enable Proton support for their game in BattleEye by emailing BattleEye developers.