Valve has expanded the software compatibility layers for its Steam Frame VR headset. In addition to the existing Proton layer, which enables Windows games to run on Linux-based SteamOS, the company has introduced FEX and Lepton.
The FEX layer is designed for Arm-based hardware. It utilizes the open-source fex-emu project, which Valve has supported since 2018 by funding lead developer Ryan Houdek. FEX simulates x86 processor instructions on Arm chipsets, allowing games compiled for x86 to run on Arm devices via code caching and graphics library calls.
Valve engineer Pierre-Loup Griffais stated that the company is exploring SteamOS versions for other Arm devices. The goal is to ensure that users do not have to sacrifice parts of their game library due to compatibility issues when using Arm-based hardware.
Lepton is built upon the Waydroid project and allows SteamOS to run standard Android APKs within a software container. This is particularly relevant for VR, as many independent titles were originally developed for Android-based Quest headsets.
Analysis of Steam metadata by VR.org indicates that 52 out of the first 120 games labeled as 'Great on Frame' run via Lepton, accounting for approximately 43% of the total. Valve engineer Lawrence Yang noted that while the company does not restrict developers from using Lepton for other Android applications, the current focus remains on gaming.
