If you’re like me, you play a lot of games. Proton has been a godsend for me. It pretty much made it possible for me to transition entirely over to Linux from Windows. Some games still don’t work with Proton, but talented folks are constantly developing new builds. This doc will walk you through installing custom builds.
You can either make your own custom Proton builds by forking the official Proton repository, or you can find open source ones on GitHub, like this one by GloriousEggroll. These custom Proton builds may fix game-specific issues, or they may just include optimizations that have yet to be released.
sudo mkdir ~/.steam/root/compatibilitytools.d to create a directory where your custom Proton builds will reside~/.steam/root/compatibilitytools.d/sudo mkdir ~/.var/app/com.valvesoftware.Steam/data/Steam/compatibilitytools.d/ to create a directory where your custom Proton builds will reside~/.var/app/com.valvesoftware.Steam/data/Steam/compatibilitytools.d/Now your game will run using the custom Proton build you installed. You can add any custom Steam Play compatibility tools into the compatibilitytools.d directory and Steam will identify it and allow you to use it on your games. I hope this brief article helps someone out!