The Steam Deck might be the most popular Linux PC ever, though you’d be forgiven if you haven’t realized that its SteamOS software is technically Linux. The Proton compatibility layer is the Steam Deck’s special sauce,

Eagle-eyed users have spotted a test application on SteamDB suggesting that Valve is experimenting with Arm64 support for Proton, the software that enables Windows games to run on Linux systems.The changelog for ValveTestApp3043620 lists several popular games—including Left 4 Dead 2,

Valve’s Proton software makes it possible to play many Windows PC games on computers running Linux-based operating system, including Valve’s own Steam Deck handheld gaming PC. So far Proton has only been available for PCs with Intel or AMD processors based on x86_64 architecture,

Valve are likely up to something hardware-related again, report NotebookCheck. Their next chunk of plastic and wires – following the Valve Index, Steam Deck and Steam Deck OLED – could swap PC gaming’s favoured x86 architecture for ARM, the type of processor favoured by the Nintendo Switch, Macs, and mobile phones.

Valve is bridging its x86 library with ARM framework support for possible Steam games on mobile. The focus on ARM64 hints at expanded cross-platform support for SteamOS. Speculation includes Steam games on mobile and the potential development of Valve's standalone VR headset.

Valve may be developing an ARM64 version of Proton for Linux gaming. Hundreds of games, like Left 4 Dead, have been tested for compatibility using a new 64-bit layer. The potential for ARM64-based portable consoles opens exciting new possibilities.