Half-Life: Alyx Reportedly Runs Natively on Apple Vision Pro Without a Gaming PC

What was actually shown​

Udi Wertheimer posted the claim on October 5, 2026, and described it as a weekend project rather than a release. His pitch was the game "running natively on the headset itself", with no PC and no streaming.

His own account of the performance is specific:

• He says it runs at roughly 3K resolution per eye and 60 fps on his M5 Vision Pro.
• He says the image is "smoothened up to 120".
• Spatial Insiders reads that as the game rendering 60 frames per second, with smoothing filling the display updates in between. Wertheimer's own wording doesn't spell this out, so treat that reading as an interpretation.
• PC Guide quotes VR enthusiast Brad Lynch calling the result "visually indiscernible" from a high-end PC. That's one person's impression, not a controlled comparison.

He tested only on the M5 Vision Pro and makes no claim about the 2024 M2 model. Nobody has published frame-time data, scene lists or settings.

How it reportedly works​

Two existing pieces of software do most of the work. Wertheimer says the project combines Valve's Linux ARM port of Alyx with Klepton, an open-source project for running Android VR apps on Vision Pro.

Valve's ARM port. Valve's Steam update notes for Alyx describe a major update adding Steam Frame standalone support. Valve's port gave Vision Pro's Apple Silicon, which is also ARM, a native build to start from. The update notes list:

• an ARM64/aarch64 port;
• rendering and performance optimizations;
• foveated rendering for standalone play;
• depth reprojection for smooth play at lower frame rates.

PC Guide reports that Valve said the work took about a year and a half. Without it, as PC Guide puts it, the Vision Pro project likely wouldn't be possible.

Klepton. It calls itself a "JIT-less relinker and compatibility layer" for running Quest and Android XR APKs on visionOS and macOS. It rewrites Android shared libraries into Apple ones. It also translates OpenGL ES through ANGLE's Metal backend and routes Vulkan through MoltenVK.

Klepton's README lists a number of working titles, including Beat Saber, BONELAB, SUPERHOT VR, Half Life, Half Life 2 and Portal. Half-Life: Alyx is not on that list. The README also says the project focuses on "Java-thin" apps with no ART or JVM.

The gap in the story​

Klepton is built around Android ARM64 APKs. Valve's Alyx port is Linux ARM64. Wertheimer says the Valve port isn't technically an Android APK, but "it's close enough", and that Claude "was able to fill in the blanks".

That sentence is the only public explanation of how the two were joined. Nobody has shown the code, the prompt history or a breakdown of who did what. Claude's role should be read as his description, not a documented architecture. His own optimization work on the M5 headset is the other half of what he credits.

Not available yet​

Don't expect to install this today:

• Nothing has shipped.
• Klepton's build guide says running on a physical Vision Pro requires the headset and an Apple Developer account. It also says users must supply their own APKs and large data files.
• Valve hasn't said it supports or endorses the project, and the Steam update notes cover Steam Frame only.
• Wertheimer says he plans to put a guide and tools on GitHub so others can build it with their own AI agents. He also says he has found an easy install route coming "VERY SOON", with a signup page attached. That is a waitlist, not a release.

It's also unclear how the hardware matters. Apple's October 2025 announcement says the M5 Vision Pro renders 10 percent more pixels than the previous generation. Those are display specs and say nothing about how Alyx performs. The PC Guide report adds that the M5's GPU gained hardware ray tracing and mesh shading, and that the refresh rate rose from 100Hz to 120Hz. Whether the M2 headset could manage the same is open.

Why PC users might care​

Valve's investment in an ARM64 build of a six-year-old PC VR game now has a use outside its own headset. That doesn't make it a general method. It is one developer, one headset model and one game. It does show that a native ARM port, plus a compatibility layer, can get a heavy PC VR title onto a headset-class chip without streaming.

There's also an AI-assisted porting angle. PC Guide notes that fan-made mods increasingly lean on AI coding tools. How much Claude contributed here is unknown, so the real test will be whether the promised guide lets other people reproduce the result.

What to watch​

• A public build or guide, and whether it works for anyone other than the original developer.
• Independent testing on both M5 and M2 Vision Pro hardware.
• Whether the 120 figure turns out to be rendered frames or reprojected display updates.
• Any response from Valve about third-party use of its ARM build.

Until then, this is an impressive demo that has been reported but not independently confirmed.