With today's update to Steam Client you no longer need to opt-in to the beta. The Steam Client now includes Steam Play (what let's you play Windows games on Linux) for all users. It's only available for whitelisted games by default. If you want to (try to) play not yet whitelisted games, also do the following:
- Open the Steam > Settings menu. On the Steam Play page (select it in the left sidebar) tick the "Enable Steam Play for all titles" box.
- Steam Client needs to restart to enable this.
They note:
- Windows games with no Linux version currently available can now be installed and run directly from the Linux Steam client, complete with native Steamworks and OpenVR support.
- DirectX 11 and 12 implementations are now based on Vulkan, resulting in improved game compatibility and reduced performance impact.
- Fullscreen support has been improved: fullscreen games will be seamlessly stretched to the desired display without interfering with the native monitor resolution or requiring the use of a virtual desktop.
- Improved game controller support: games will automatically recognize all controllers supported by Steam. Expect more out-of-the-box controller compatibility than even the original version of the game.
- Performance for multi-threaded games has been greatly improved compared to vanilla Wine.