Anti-cheat software are tools designed to prevent cheating in games. Anti-cheat software typically prevents games from running on Linux, since these anti-cheats don't have Linux support integrated. With the recent addition of Linux support to the most popular anti-cheat software, many games have started supporting Linux as well.
Games with anti-cheat
You can see which games that use anti-cheat have enabled Linux support here.
The most popular anti-cheat software are Easy Anti-Cheat , BattleEye, and VAC. Both Easy Anti-Cheat and BattleEye have support for Linux via Proton, while VAC supports Linux natively.
Easy Anti-Cheat added Linux Proton support in late 2021 with the then-latest version of the Epic Online Services Easy Anti-Cheat software development kit (SDK). Some games, however, don't use the Epic Online Services version of Easy Anti-Cheat, meaning they must perform a large upgrade of their Easy Anti-Cheat SDK before they can add Linux support via Proton. As the older Easy Anti-Cheat SDK becomes obsolete though, game developers will have to upgrade to the newer SDK, allowing them to easily add Linux support.
BattleEye Proton support became supported in late 2021. Developers can enable Proton support for their game by emailing BattleEye developers.