Independent Project Brings Valve SteamOS to Apple Silicon Macs

An independent software project known as FX Steam Launcher has made it possible to run Valve's official SteamOS on Apple Silicon Macs. Utilizing the ARM64 version of SteamOS originally developed for Valve's Steam Frame, the open-source software brings the complete Steam gaming interface and Windows game compatibility directly to macOS.

Unlike a native operating system installation, the launcher operates SteamOS inside a virtual machine through Apple's Hypervisor.framework and libkrun, functioning similarly to DroidDeck projects on Android. The software supports SteamOS Gaming Mode, the KDE Plasma Desktop Mode, audio output, controllers, and GPU acceleration, allowing users to run SteamOS in a window or fullscreen while keeping access to macOS.

Compatibility for Windows titles relies on Proton 11 for ARM64 alongside FEX to translate x86 instructions. For graphics, DirectX 9, 10, and 11 games utilize DXVK, whereas DirectX 12 titles depend on vkd3d-proton. Graphics instructions subsequently pass through Mesa Venus and either MoltenVK or KosmicKrisp before reaching Apple's Metal API, with the project also offering experimental support for DXMT.

The software requires Apple Silicon Macs running macOS 15 or newer, while the KosmicKrisp component mandates macOS 26 or later for DirectX 12 feature level 12_0 support. Developers have equipped the launcher with configurable CPU and memory allocations, MetalHUD monitoring, and compatibility with various controllers such as Xbox and DualSense devices.

YouTuber ETA Prime recently tested the project on a MacBook Pro powered by an Apple M4 Max chip containing a 14-core CPU, 32-core GPU, and 36GB of unified memory. Testing demonstrated varying performance metrics locally through SteamOS, ranging from over 70 frames per second in The Witcher 3 to more than 200 frames per second in Left 4 Dead 2, while Stellar Blade achieved over 70 frames per second on High settings at 800p.

Despite impressive performance milestones, testers noted several technical hurdles. The Witcher 3 exhibited incorrectly rendered trees, and multiple games suffered from stuttering during shader compilation. Furthermore, titles such as DOOM Eternal, Marvel’s Spider-Man: Miles Morales, and Ghost of Tsushima failed to start due to unsupported hardware detection or startup crashes.

The FX Steam Launcher remains under active development by its independent creators. Version 1.9.8, which was released on November 2, successfully restored compatibility with the SteamOS 0.6.0 preview following a Valve update that had previously prevented the virtual GPU from initializing properly.