FX Steam Launcher Finally Makes Official SteamOS Run on Apple Silicon Macs

Apple Silicon Macs have sat outside Valve’s gaming plans for years, yet a single open-source effort on GitHub now places the company’s own ARM64 SteamOS image inside a lightweight virtual machine on those same machines. The project, called steamac and released as FX Steam Launcher, downloads Valve’s signed Steam Frame build, verifies the checksum, and boots it through Apple’s Hypervisor framework with libkrun. Once running, the familiar Steam gamepad interface appears in a Mac window, complete with controller support and CoreAudio sound, while Windows games arrive through Proton and the FEX emulator.

Graphics travel a long way before appearing on your screen. A game first performs DirectX calls, which are then transformed to Vulkan inside the virtual machine using DXVK. Those commands then jump out of the guest and land on the Mac side of things via virtio-gpu and Venus, where they are passed off to either MoltenVK or the new KosmicKrisp driver, which is still in beta, depending on the parameters. Either driver just converts Vulkan into Metal, leaving the actual work to Apple’s silicon GPU. Users may choose which driver to use, and it’s actually quite easy.

All you need to get started is an Apple silicon Mac running at least macOS 15 and enough free disk space to generate a modest sparse image that will increase as you add more games. There are also pre-built DMG editions of FX Steam Launcher that have already been signed and notarized, making the process quite straightforward. Simply drag the file into your Applications folder, create a disk, and follow the prompts to accept Valve’s licenses. Building from source still requires some familiarity with Xcode, Homebrew, and a Linux container environment for the kernel and Mesa bits, but the project has all of that covered for you.

Early tests on a MacBook Pro with an M4 Max chip indicate encouraging results, with the stack producing playable frame rates. The Witcher 3 runs at around 70 frames per second at 1080p on high settings, however tree rendering does periodically break. Left 4 Dead 2 averages 140 frames per second and occasionally exceeds 200. Fallout 4 is more cantankerous, locking at 60 frames per second on medium settings and the same resolution. Even older titles like Skyrim and Grand Theft Auto IV run rather smoothly, however it’s worth noting that with six layers between the Steam client and the metal GPU, some graphical anomalies are sure to arise.

Controllers are also quite simple to set up, as they are mapped into the guest as virtual Xbox and DualSense devices using GameController.framework, and if you have an actual DualSense pad laying around, you can even get it to pass through with rumble and touchpad support on the other side. If you want a full desktop experience, you can open a Plasma session in a nested window under Desktop Mode, and there are per-game profiles that allow you to change graphics pathways or Vulkan drivers without rebooting.

They recently released 1.9.8, which addressed certain SteamOS 0.6.0 compatibility issues when Valve altered a library that was causing the client to become stuck on startup. It also resolved a logging issue on M3, M4, and M5 chips. There’s also a second fork that aims to improve Easy Anti-Cheat handling for games like VRChat, albeit the results vary depending on the title.