Lumote is a colorful platform puzzle game with some surreal visuals. The demo is free and runs great in Proton. I didn't even force a Proton version, just used the default and it ran fine.
Specs:
Mint 19.3 64-bit
GeForce GTX 1060
Nvidia 430.50
https://store.steampowered.com/app/791240/Lumote/
Specs:
Mint 19.3 64-bit
GeForce GTX 1060
Nvidia 430.50
https://store.steampowered.com/app/791240/Lumote/