What is ProtonDB?

ProtonDB is an unofficial community website that collects and displays detailed data on how an individual got a particular game to work. It tells you what Linux distribution, kernel version, graphics card type along with driver version, and last but not least, commands for launch options. The rating scale is from "Borked" to "Platinum". 

The rating scale as written on ProtonDB

Platinum: Runs perfectly out of the box

Gold: Runs perfectly after tweaks

Silver: Runs with minor issues, but generally is playable

Bronze: Runs, but often crashes or has issues preventing from playing comfortably

Borked: Either won't start or is crucially unplayable

There’s about 100 games every month that get a Platinum rating according to ProtonDB. Platinum sets the bar high. Games with that rating just work out of the box like native Windows 10 or macOS 10 games without requiring end-user tweaking.

The biggest problem to overcome is the anti-cheat software that's required for many multiplayer games. Valve is working on that issue with services like Easy Anti-Cheat, but as of this posting I honestly don't see anything with that changing soon.