VideoCardz reported that FX Steam Launcher 1.9.8 restored compatibility with the SteamOS 0.6.0 preview on November 2, 2026, after a Valve update disrupted virtual-GPU initialization. The change concerns that preview running through the launcher on Apple Silicon Macs.

FX Steam Launcher is a community project that runs Valve’s ARM64 SteamOS in a virtual machine, with macOS remaining the host operating system. The project uses Apple’s Hypervisor.framework and libkrun; it does not replace macOS with a native SteamOS installation. Its project repository describes how the setup allocates a Mac’s memory.

How FX Steam Launcher allocates Mac memory

The launcher’s automatic setting assigns half of the Mac’s RAM to the virtual machine, within a range of 4 to 16 GiB. It reserves at least 3 GiB or 25% of host memory for macOS, other apps and driver overhead, then assigns the remainder to a graphics budget.

For a 16-GiB Mac, the project’s example assigns 8 GiB to the virtual machine, 4 GiB to graphics and 4 GiB to the host reserve. So the Mac’s installed memory is divided among the virtual machine, graphics and macOS rather than all going to the game. ETA PRIME recommended at least 24 GB of host memory for more demanding games.

What game demonstrations on Macs show

A first-person shooter scene with a weapon in the foreground, character health bars along the bottom and performance readouts in the upper corners.
ETA PRIME’s English-language demonstration of SteamOS and game tests on Apple Silicon Macs.
iHaadi’s English-language M2 MacBook Air walkthrough, including one HoloCure test.

ETA PRIME’s reported M4 Max MacBook Pro test used a 14-core CPU, a 32-core GPU and 36 GB of unified memory; about 19 GB was allocated to the virtual machine. In that demonstration, Stellar Blade ran above 70 fps at 800p High, the original The Witcher 3 exceeded 70 fps at 1080p High, Fallout 4 reached its 60-fps cap at 1080p Medium, and Skyrim reached 60 fps at 1080p High. Red Dead Redemption exceeded 70 fps at 1080p Medium but dropped into the 40s, while Grand Theft Auto IV exceeded 100 fps at 1080p Medium. VideoCardz also summarized these tests by ETA PRIME.

The results varied by game. The Witcher 3 had incorrectly rendered trees, and Marvel vs. Capcom: Infinite stuttered during shader compilation. DOOM Eternal launched but stopped after detecting an unsupported GPU; Marvel’s Spider-Man: Miles Morales and Ghost of Tsushima failed to start. On an M6 Mac mini with 16 GB of RAM, ETA PRIME reported memory swapping when running more demanding games.

A separate walkthrough by iHaadi used an M2 MacBook Air and showed HoloCure running at 60 fps. That is one game on one Mac configuration.