An open-source project called FX Steam Launcher brings a version of SteamOS to Apple Silicon Macs, running the operating system in a virtual machine rather than installing it natively. The project is based on the ARM64 build developed for Steam Frame and uses Proton 11 and FEX to run Windows games, alongside SteamOS’s interface.
The launcher is available through GitHub. After installation, it downloads an official SteamOS image from Valve and can also manage operating system updates. It supports Apple Silicon Macs running macOS 15 or later, although some components require a newer system.
Running games involves several translation layers. DXVK handles DirectX 9, 10 and 11 titles, while DirectX 12 games use VKD3D-Proton. Graphics instructions then pass through MoltenVK or KosmicKrisp before reaching Apple’s Metal API. KosmicKrisp requires macOS 26 or later. The project also offers experimental DXMT support for running DirectX 10 and 11 games without VKD3D-Proton.
In tests shared by YouTube creator ETA Prime, The Witcher 3, Stellar Blade and Left 4 Dead 2 ran on an Apple M4 Max. The games exceeded 70 frames per second at high settings, while Left 4 Dead 2 surpassed 200 fps. However, Stellar Blade was tested at 800p and the other games at up to 1080p; the results do not represent every title or performance scenario.
SteamOS can run in either a window or full screen, with macOS still accessible. The project remains unofficial, and its compatibility depends on the game and the software layers required to run it.
Sources: PC Gamer.