Steam Play/Proton for GNU/Linux update supports more games (including non-Steam games)

What is Proton?
Proton is a tool distribution based on a modified version of Wine. The included improvements to Wine have been designed and funded by Valve, in a joint development effort with CodeWeavers. Proton itself is released under a permissive license similar to the MIT license. The code forked from WINE was originally licensed under the Lesser GNU Public License (LGPL), which requires derivative works to also be under the LGPL. It will allow Linux to play many games, as well as providing developers a development target without making a full port. Proton uses the Vulkan graphics API to translate DirectX 11 and 12, leading to better compatibility and performance.

"Some" Windows games with no GNU/Linux version currently available can now be installed and run directly from the Linux Steam client with native Steamworks and OpenVR support. Steam Play officially supports a limited set of "whitelisted" games that are deemed Proton-compatible and play on GNU/Linux. Being on the whitelist means that a Windows game will run, but there may be moderate performance decreases compared to running the game natively on Windows. One game that is whitelisted is Wolfenstein: The Old Blood. It was released for Windows in 2015 and is powered by id Tech 5. It works just fine on the NVIDIA Linux stack and Mesa.

Any game that has major bugs will not be put on the whitelist. Games with crazy DRM or anti-cheat systems will be hard and will never be supported. Based on reports on ProtonDB,many non-whitelisted games play just as well as on Windows including many popular titles like King of fighters XIV and The Elder Scrolls Online. In fact around 700 titles are noted on ProtonDB as “stable,” meaning they have minor issues but remain playable. Results will vary depending the exact hardware and driver configurations one is using.

My test systems:

Desktop:Xfce 4.12.3
Proton:3-7-8 
Distro:MX-18_x64
Kernel:4.19.0-1
RAM:12 GB
GPU Driver:4.3 Mesa 18.2.6
GPU:AMD RX 560 4GB
CPU:Intel i7 4770 3.6 GHz

Desktop:Big Picture Mode
Proton:3.16-5
Distro:SteamOS 2.0
Kernel:4.16.0-0.steamos2.1-amd64
RAM:16 GB
GPU Driver:NVIDIA 396.54
GPU:MSI GeForce GTX 1070 Ti AERO 8G
CPU:AMD Ryzen 7 2700

Wolfenstein: The Old Blood and TEKKEN 7 Ultimate Edition runs perfectly. They are both white list games. I've started doing my own testing and have been pleasantly surprised with games like: King of fighters XIV,The Elder Scrolls Online, and Quake Champions. All three are games that previously only relied on a Windows 10 installation. All are completely stable and exhibit native-like performance with very-very few bugs or errors.