Valve has introduced a new rating system to check the game compatibility with an upcoming game console by Valve, Steam Deck. Valve divides the games into four-game compatibility levels: verified, playable, unsupported, and unknown.
There are some requirements for the game that have to be met to be verified as Deck compatible:
The game should have full controller support, use appropriate controller input icons, and automatically show up the on-screen keyboard when needed.
The game should support Steam Deck default resolution (1280×800 or 1280×720), have good default settings, and text should be clear.
The game should not show any compatibility warnings, and there’s a launcher that is navigable with a controller.
If the game runs through Proton, the game all its middleware should be supported by Proton. This includes anti-cheat support.
For full information about the game verification process, check it on the Steam website.