NotProton README

The project's README from github.com/NotProtonNot/NotProton. As one markdown file: README.md.

NotProton

NotProton enables the Steam Play experience from Linux Steam in the macOS Steam client.

This is done by forcibly enabling the Steam Play functionality in macOS Steam (which is present and inert) as well as by porting some components of Valve's Proton to macOS.

This tool is intended to be used with Steam Client 1788652215 or 1790121765 and CrossOver 26.3 or CrossOver Preview 20261006 or 2026082. Both the FEX and the Rosetta versions are supported. I recommend using the FEX version of the Preview 20261006, as it includes both the FEX version as well as the Rosetta one.

The macOS app itself is located in the app folder. The core logic is in dylib. lsteamclient is a macOS port of Valve's lsteamclient. steam-shimis a port of Valve's steam-helper from Proton 9. ntdll-patch patches the copy of CrossOver that the app makes/places in the ~/Library/Application Support/notproton/runners/ folder so that lsteamclient is loaded.

This release is coming several days past when I wanted to release it, so the documentation is quite sparse. Sorry about that, I'll improve it shortly. For real this time.

Please read NOTICE for license information.

Please open issue reports with any issues. PRs are welcome and encouraged. Contributions policy to come shortly.

There are many people who worked on similar ideas, similar projects. I did not base NotProton on their work, but I still want to give thanks to the people who came before me:

Nat Brown made Kaon, which is similar in goals to NotProton.

mont127's Neutron is also a similar idea, but implemented differently.

Gio was working enabling Steam Play inside of Steam on macOS prior to the release of NotProton itself. I would have done things differently had I been aware of that.

Thanks to everyone who has positively contributed to macOS gaming.

NotProton (NotProtonNot/NotProton)

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NotProton
What is this?NotProton unlocks the 'Steam Play' feature of the Linux Steam client inside the macOS Steam app, letting Windows-only games run on a Mac through a ported version of Valve's Proton.
Is this a standalone app, or does it modify my existing Steam install?It is a small macOS app plus a set of patches; it forcibly flips a hidden Steam Play toggle that already exists but is inert in macOS Steam, and patches the copy of CrossOver that Steam bundles so the ported lsteamclient library gets loaded.
How do I get this running?You need the exact Steam Client build it targets (1788652215 or 1790121765) along with CrossOver 26.3, CrossOver Preview 20261006, or 2026082; the macOS app itself sits in the release folder and its ntdll-patch component patches the CrossOver copy Steam creates.
Do I need CrossOver installed, or does it work with Steam alone?Yes, CrossOver is required to actually run the Windows side of games; NotProton patches the copy of CrossOver that the Steam app places in its own folder so the ported lsteamclient loads.
Is this a polished, ready-to-use release?Not really yet - the author admits the release shipped later than planned so documentation is sparse, and it only works with specific pinned Steam Client and CrossOver build numbers rather than any version.
What's the difference between the FEX and Rosetta versions?Both are supported translation-layer options for running the ported Proton pieces; the author recommends the FEX build of CrossOver Preview 20261006 because that one package bundles both the FEX and Rosetta variants together.
What is lsteamclient in this project?It's NotProton's macOS port of Valve's lsteamclient, the component that lets the Steam client itself communicate with games running under the ported Proton compatibility layer.
Did the author build this completely from scratch?No - the README credits earlier similar efforts, Nat Brown's Kaon, mont127's Neutron, and Gio's prior work on Steam Play for macOS, as inspiration, though NotProton's own code was not based on theirs.
What are similar projects?Whisky, Madeira, TheSimpsonsGameRecomp, highball, Wind-Waker-Recomp, ShadowOfTheColossus-PC, OpenEmu, ReSkate
Which topics is it in?wine, compatibility-layer, scala, game-modding, emulation, modding, gpl, emulator, game, macos-app, gaming, reverse-engineering
Creator
NotProtonNot
Size
58.2 MB
Stars
1.7K
Updated
CommitOct 16Releasev1.1.9Oct 16
Age
24d
Commits · 90 Days