Run Beat Saber 1.44.1 as a native Windows ARM64 program on ARM64 Linux under Proton, tested on the Steam Frame, instead of emulating the x64 build with FEX.

The game's engine and C# code both run natively. Only Proton's small steam.exe launcher stays x64.

Numbers come from SteamVR's per-session compositor stats, at a 120 Hz target:

With FEX, the retail game ran at about 90 fps and dipped to about 55. With the native build, the frame drops are gone.

A CPU micro-benchmark run inside the game's Mono runtime shows the same thing: native code is 2–3× faster than FEX-translated x64 on everything except Vector3 math (see docs/FINDINGS.md).

Turn off Adaptive SFX: Solo → song selection → Player Settings tab in the panel next to the song list (not the main menu's Options). It measures the song's loudness on the audio thread with thousands of Math.Pow calls per second. On x64 that's cheap; on ARM64, Mono's pow is slow and the measurement takes most of the audio thread. With it off, frame times were steadier in a replay benchmark: 30 % fewer frames over 9.5 ms at 120 Hz. The trade-off: hit sounds no longer adapt to the song's loudness. See docs/FINDINGS.md.

In the game's graphics settings, turn off Screen Distortion. For the effect, the game copies the whole scene in the middle of every frame and keeps drawing on it, which costs a lot of GPU time on the Frame's tiled GPU. In v0.1.6 it also caused frozen ghost images of the menu and sabers.

With foveated rendering the Frame's GPU renders the area you look at in full resolution and the edges at lower resolution. bs-arm64 uses SteamVR's own foveated rendering (Valve's fdm_injection layer), the same one Steam turns on for the x64 game with Properties → Performance → Foveated Rendering. With SteamVR's eye tracking the sharp area follows your eyes.

By hand, start the game with bs-arm64.sh launch --foveation. That sets what Steam sets: FDM_DEBUG=enable and VK_INSTANCE_LAYERS=VK_LAYER_VALVE_rpo:VK_LAYER_VALVE_fdm_injection. Steam's default is mild; FDM_DEBUG=enable,med or FDM_DEBUG=enable,hi saves more and is easier to notice. BSManager's ARM64 tab doesn't set these yet.

One run each, headset off (no eye movement). bs-arm64 0.2.0's own foveated rendering got 3.16 ms GPU and 5.37 ms CPU in the same test, so it was removed.

AssetBundleLoadingTools' Enable Multi-Pass Rendering (Mod Settings, or EnableMultiPassRendering in UserData/AssetBundleLoadingTools.json) makes the game draw everything twice, once per eye. It also kept 0.2.0's foveated rendering off; Valve's layer hasn't been tried with it. Check it when you copy UserData over from a Windows install.

The ARM64 player comes from the same Unity version the game was built with (6000.0.40f1). Every native piece around it that only existed as x64 or ARM64EC has an ARM64 replacement. Details are in docs/ARCHITECTURE.md.

The Steam Frame fork of BSManager, DaVarga/bs-manager (ARM64 AppImage on its releases page), fixes BSManager for ARM64 Proton and adds an ARM64 tab next to Mods for 1.44.1 instances. That tab downloads the release matching your Proton build and installs, reinstalls or removes it, with or without mod support. It also re-applies the ARM64 mod loader fixes after BSIPA is installed, and sets up the launch environment.

Follow its Steam Frame guide. On a fresh Frame, three things trip people up:

• Install Proton 11.0 (ARM64) (and Steam Linux Runtime 4.0 for arm64) from the Steam library (Tools) first; BSManager asks for the Proton folder.
• Add DISABLE_VULKAN_FDM_INJECTION_LAYER=1 %command% as launch command in BSManager. Without it the game hangs at startup: Valve's foveated rendering layer is half on outside Steam. For foveated rendering in the x64 game, use FDM_DEBUG=enable VK_INSTANCE_LAYERS=VK_LAYER_VALVE_rpo:VK_LAYER_VALVE_fdm_injection %command% instead.
• Launch 1.44.1 once before clicking Install in the ARM64 tab. That creates BSManager's Wine prefix. If Install already failed with Wine prefix … does not exist, the version is left half changed; launch another version once, then click Install again.

On the Steam Frame, with BSManager, a 1.44.1 instance, and "Proton 11.0 (ARM64)":

Download the release tarball that matches your Proton version (<Proton dir>/version) from the releases page, then on the Frame:

tar xf bs-arm64-*.tar.gz && cd bs-arm64-*/
./bs-arm64.sh install ~/.local/share/BSManager/BSInstances/1.44.1   # downloads the Unity player etc.
./bs-arm64.sh launch  ~/.local/share/BSManager/BSInstances/1.44.1

Or build it yourself:

# 1. build the open-source parts (any Linux host, x86_64 or aarch64); see docs/BUILD.md
./build.sh
# 2. copy the repo (with out/) to the Frame, then there:
install/bs-arm64.sh install ~/.local/share/BSManager/BSInstances/1.44.1
install/bs-arm64.sh launch  ~/.local/share/BSManager/BSInstances/1.44.1
# undo:
install/bs-arm64.sh uninstall ~/.local/share/BSManager/BSInstances/1.44.1

See docs/INSTALL.md for every file that gets touched.

Status: verified end to end on the Frame. A clean build.sh output was installed with install/bs-arm64.sh into a fresh copy of a BSManager 1.44.1 instance: Steam, VR and maps all work.

• docs/ARCHITECTURE.md: every component, and why it's needed
• docs/BUILD.md: build requirements and steps
• docs/INSTALL.md: what the installer changes, launching, uninstalling
• docs/FINDINGS.md: the debugging path, pitfalls, and the benchmark
• docs/LEGAL.md: licenses, and what may or may not be redistributed

MIT (see LICENSE) for the original code. The patches follow their upstream licenses. This project is unofficial and not affiliated with Beat Games, Valve or Unity. See docs/LEGAL.md.