On September 20, Valve pushed changes to a test application visible on SteamDB indicating a massive list of games being tested with its Proton compatibility layer. Interestingly, there now also seems to be an ARM64 version of Proton, which exists to make Windows games playable on Linux. This version of Proton, "proton-arm64ec-4", is listed as being tested with literal hundreds of games, but popular titles like Left 4 Dead 2 and Shadows of Mordor stick out here, showing a wide range of possibilities with ARM64 Proton behind the scenes.
Now, what does all of this mean? While Valve has yet to make any kind of official announcement regarding ARM64 support on SteamOS, or for Proton, it clearly seems to be a priority and part of its push for gaming on Linux, in general. Now, though, Valve seems to want to expand its Linux gaming audience from just x86 hardware, and start folding in Linux Arm devices in line with ongoing efforts to improve gaming on Windows for Arm. There are also some mentions of Waydroid, which means even Android Arm devices may be getting Proton support, which would surely expand its audience significantly.
Now, some suggest that this means Valve must be developing its own Arm devices — perhaps an even cheaper alternative to Steam Deck — but truthfully, this seems quite unlikely, particularly considering the already-low entry price of Steam Deck. More pressingly, introducing a yet lower, yet more obscure Arm gaming device tier alongside the Steam Deck and its eventual successors seems a questionable idea at best. However, improving support for Arm devices, in general, is certainly in line with Valve's established history of backing the Linux gaming scene versus the locked-down Windows ecosystem.
Considering the early stage of Arm gaming on Windows, Valve's work on Proton for Arm also raises some interesting long-term questions for existing Arm devices, especially the high-end Snapdragon X chips. Depending on how things shake out, we may eventually end up with a Linux Arm gaming experience that is overall superior to actual Windows for Arm gaming, which would be a real treat for proponents of Linux. As it currently stands, a very large number of games confirmed to work on Windows for Arm are already listed as being tested by Valve in these SteamDB changes.
