01Modders bring full SteamOS to Apple Macs, Windows games already playable - VideoCardz

Full SteamOS now runs on Apple Macs, Windows games tested at over 200 FPS
An independent project called FX Steam Launcher has made it possible to run Valve’s official SteamOS on Apple Silicon Macs. The software uses the ARM64 version of SteamOS developed for Valve’s Steam Frame, bringing the complete Steam gaming interface and Windows game compatibility to macOS. The project is open-source and available on GitHub.
Unlike a native installation, FX Steam Launcher runs SteamOS inside a virtual machine using Apple’s Hypervisor.framework and libkrun. So the idea is similar to DroidDeck, which is basically a full SteamOS running on Android.
The Apple version supports SteamOS Gaming Mode, KDE Plasma Desktop Mode, controllers, audio and GPU acceleration. Users can run SteamOS in a window or fullscreen, while retaining access to macOS. The launcher also downloads the official SteamOS image directly from Valve and supports operating system updates.
SteamOS on Mac supports DirectX 12 through multiple translation layers
Windows game compatibility relies on Proton 11 for ARM64 and FEX for translating x86 instructions to ARM64. DirectX 9, 10 and 11 games use DXVK, while DirectX 12 games rely on vkd3d-proton. Graphics instructions then pass through Mesa Venus and either MoltenVK or KosmicKrisp before reaching Apple’s Metal API. The project also offers experimental DXMT support, which allows DirectX 10 and 11 games to use Metal without the Vulkan translation layer.
The launcher supports Apple Silicon Macs running macOS 15 or newer. However, KosmicKrisp requires macOS 26 or later and offers DirectX 12 feature level 12_0 support. Games requiring feature level 12_1 or Shader Model 6.6 remain unsupported. The developers also provide configurable CPU and memory allocations, MetalHUD monitoring, mouse and keyboard support, and compatibility with Xbox, DualSense and other controllers.
Apple M4 Max tested in Windows games, reaches over 200 FPS in Left 4 Dead 2
YouTuber ETA Prime tested the project on a MacBook Pro equipped with an Apple M4 Max featuring a 14-core CPU, 32-core GPU and 36GB of unified memory. The test included several Windows games running locally through SteamOS, with results ranging from more than 70 FPS in The Witcher 3 to over 200 FPS in Left 4 Dead 2. Stellar Blade also ran at over 70 FPS using High settings at 800p.
| Game | Resolution / settings | Reported performance |
|---|---|---|
| Stellar Blade | 800p, High | 70+ FPS |
| The Witcher 3 (original) | 1080p, High | 70+ FPS |
| Left 4 Dead 2 | 1080p, High | 200+ FPS |
| Fallout 4 | 1080p, Medium | 60 FPS, capped |
| Red Dead Redemption | 1080p, Medium | 70+ FPS, drops into the 40s |
| Grand Theft Auto IV | 1080p, Medium | 100+ FPS |
| Skyrim | 1080p, High | 60 FPS |
| Marvel vs. Capcom: Infinite | 1080p, Medium | Playable, shader stuttering |
The results are not without issues. The Witcher 3 displayed incorrectly rendered trees, while several games experienced stuttering during shader compilation. DOOM Eternal launched but refused to run because it detected an unsupported GPU. Marvel’s Spider-Man: Miles Morales and Ghost of Tsushima also failed to start.
ETA Prime initially tested the software on an M6 Mac mini with 16GB RAM, which managed over 140 FPS in Left 4 Dead 2 but struggled with more demanding games due to memory swapping. On the M4 Max MacBook Pro, approximately 19GB was allocated to the VM. ETA Prime recommends at least 24GB RAM for more demanding games, although less demanding titles can work on 16GB systems. Increasing the VM allocation beyond the eight performance cores of the M4 Max also reduced performance in some tests.
FX Steam Launcher is still under active development. Version 1.9.8, released November 2, restores compatibility with SteamOS 0.6.0 preview after a Valve update prevented the virtual GPU from initializing.
Apple Gaming
So, is this finally the moment when gamers can start taking Apple M-series devices seriously? Perhaps. The bigger question is why it took independent developers to make this happen, rather than Apple and Valve working together. I guess 2026 is the year where software crosses all proprietary hardware limitations.
Source: FX Steam Launcher GitHub, ETA Prime




























