Valve forks Wine to Proton

n 2010, we announced Steam Play: a way for Steam users to access Windows, Mac and Linux versions of Steam games with a single purchase. More than 3000 of the games that have been added to Steam after that point have included Linux support, with more titles being added every day. Since then, we've continued to look for ways to make more titles easily accessible to Linux users.So, two years ago, we started an effort to improve the quality and performance of Windows compatibility solutions for Steam games. A lot of our work has been in the form of supporting Wine and other existing compatibility projects. We have also been integrating these tools into the Steam client to provide the same simple plug-and-play experience offered by regular Linux games.[...]As a result of this work, today we are releasing the Beta of a new and improved version of Steam Play to all Linux users! It includes a modified distribution of Wine, called Proton, to provide compatibility with Windows game titles.

Proton is available as open source on GitHub.