Modern Apple computers do not support older 32-bit programs, which has cut their owners off from many classic games. Now those machines can run, for example, Left 4 Dead 2 at up to 200 frames per second. This is made possible by FX Steam Launcher, an app developed as an open-source project on GitHub.
What FX Steam Launcher is
The open-source FX Steam Launcher project lets owners of Macs with M-series processors install SteamOS, a gaming operating system. It is downloaded from Valve's servers and runs inside a virtual machine, in a separate window or full screen, without interfering with macOS itself. Users get Steam's Game Mode and the KDE Plasma desktop, just as on the Steam Deck handheld, but without complicated manual setup. Windows games built for the x86 architecture run without any help from their developers: the Proton compatibility layer lets Windows programs work in a Linux environment, while the FEX code translator converts their instructions into the language of Apple's processors.
How it works
To get Windows games running on ARM-based Macs, the developers built a multilayered system of translations. FX Steam Launcher does not emulate an x86 computer; SteamOS itself runs on the Apple chip as a native ARM system. Launching games falls to a combination of several technologies. The Proton compatibility layer allows Windows applications to run in a Linux environment, and the FEX code translator converts game instructions on the fly from the x86 architecture to ARM, the architecture used by Apple's processors. Graphics commands also pass through several stages of conversion: the DXVK and vkd3d-proton libraries translate DirectX 9–12 calls into the Vulkan standard, and then dedicated layers such as MoltenVK convert them into commands for Metal, Apple's graphics technology.
What the system can do
Performance depends on the computer model. The blogger ETA Prime tested the system on a MacBook Pro with an M4 Max chip, 14 CPU cores and 32 GPU cores, and 36 gigabytes of unified memory. In The Witcher 3, at 1080p and high graphics settings, the system delivered more than 70 frames per second. The classic shooter Left 4 Dead 2 ran on the same machine at an average of 140 frames per second, topping 200 in some scenes. Fallout 4 held a steady 60 frames per second at 1080p and medium settings, as did Skyrim on high settings. In Grand Theft Auto IV, the frame rate exceeded 100.
How to install it
Installation requires a Mac with an Apple Silicon processor running macOS 15 or later. You will also need about 20 gigabytes of free disk space for a so-called sparse image, which takes up space only as it fills. The installation process is simple: download the DMG installer from the latest release on the project's GitHub page, drag FX Steam Launcher into the Applications folder and launch it. The app is signed with a Developer ID certificate, which Apple issues to registered developers, and has been notarized, meaning it has passed Apple's automated check for malicious code. On first launch, the program offers to create a new virtual disk and automatically downloads a SteamOS image of about 4.5 gigabytes from Valve's servers.
Limitations and potential problems
The technology has a number of limitations. Games protected by anti-cheat systems will not work if those systems block launching in virtual machines. Some modern graphics technologies, such as Shader Model 6.6 and DirectX 12 feature level 12_1, are not yet supported either, which prevents many Unreal Engine 5 titles from running. Some games may not launch at all: in testing, for example, DOOM Eternal and the Ghost of Tsushima demo failed to start. The first time a game is launched, there may be delays caused by shader compilation, the processing of graphics effects. The first shader compilation for the Stellar Blade demo on an M1 Max chip, for instance, took about 28 minutes. Some games may also show rendering glitches; in The Witcher 3, for example, trees were drawn incorrectly.
FX Steam Launcher is an enthusiast project, not an official Apple or Valve product. It continues to evolve: the recent 1.9.8 update, for example, fixed compatibility issues with the new version of SteamOS.
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