It was whispered last week, but now it's completely official. Steam Play, originally intended as a single-purchase system for buying games running on Windows, Mac and Linux, takes platform-independent compatibility to the next level. Yes, Valve is now testing running Windows games on Steam under Linux. And to the great satisfaction of Linux and open source advocates, it does this in the right way by building and supporting initiatives that not only benefit Steam, but also the entire Linux ecosystem.
To be honest, for a long time Valve has been a proponent of using industry-wide standards and technologies, even open source versions, than own options, such as using OpenGL or, now, Vulkan, via Microsoft's Direct3D API. It set foot where it had its mouth when it gambled on Linux for its SteamOS and Steam Machines, the latter of which has not yet paid much fruit. That could possibly improve with the new Valve game for Steam Play.
Valve has fortunately decided to base its new Proton tool on the existing open source WINE project (Wine Is Not an Emulator) and has even collaborated with CodeWeavers, creators of the CrossOver Office Suite with which Linux users can run Microsoft Office, based on WINE. Although Proton has Steam-specific functions, Valve has pushed some of the improvements it has made alongside the general WINE code to benefit all Linux users. And as expected, Valve still insists that developers focus on the graphical Vulcano API (or at least OpenGL) instead of Direct3D to maximize platform support.
This Steam Play feature is available to all Linux users, but they must first sign up for the Steam Client beta. For the time being, the range of whitelisted games ready for Steam Play is a bit short and varied, although Linux users can force Steam Play for all titles at their own risk. Those whitelisted games include:
• Beat Saber
• Bejeweled 2 Deluxe
• Doki Doki Literature Club!
• DOOM II: hell on earth
• DOOM VFR
• Air-raid shelter
• FINAL FANTASY VI
• Geometry Dash
• Google Earth VR
• Into The Breach
• Magic: The Gathering – Duels of the Planeswalkers 2012
• Magic: The Gathering – Duels of the Planeswalkers 2013
• Mount & Blade
• Mount & Blade: With Fire & Sword
• NieR: Automata
• PAYDAY: The Heist
• S.T.A.L.K.E.R.: Shadow of Chernobyl
• Star Wars: Battlefront 2
• Tekken 7
• The last remnant
• Tropico 4
• Ultimate Doom
• Warhammer® 40,000: Dawn of War® – Dark Crusade
• Warhammer® 40,000: Dawn of War® – Soulstorm
Valve admits that this will have some impact on performance, especially for games "where translation of graphical API is required", including those with Direct3D. However, Windows games that use Vulkan from the beginning should not make much difference, at least not in theory. Some games that use DRM or anti-cheat systems may not work at all. Although this is certainly a huge blessing for Linux gaming, it remains to be seen whether this will actually improve the market situation or whether game developers will support Vulkan or Linux less quickly because there is still a compatibility tool.