Not just Proton: Getting to know Valve's new SteamOS compatibility layers

Valve is expanding the capabilities of its Linux-based SteamOS by integrating two new compatibility layers alongside its established Proton tool.

This technical expansion aims to support the company’s new Steam Frame virtual reality headset and broaden the platform's compatibility with diverse hardware architectures. The first new addition, FEX, is a customized version of an open-source emulator designed to translate x86 processor instructions for Arm chipsets. Valve has sponsored this project for several years to ensure SteamOS can run smoothly on Arm-based hardware, potentially opening the door for the operating system to power a wider range of alternative portable devices in the future.

The second tool, named Lepton, builds upon the Waydroid container framework to allow standard Android application packages to execute on SteamOS. This layer is crucial for the Steam Frame because it enables the headset to run mobile virtual reality games originally developed for Android-based systems like the Meta Quest. Already, a significant portion of the software catalog optimized for the Steam Frame relies on Lepton to run Android executables directly, bypassing the need for traditional PC builds. This initiative reflects Valve's broader shift from demanding native Linux ports to providing robust software translation layers that seamlessly bridge different hardware and operating systems for players.