Guides / Steam library on Mac

Play your Windows Steam library inside Mac Steam

By Bridgeplay · Last updated 29 October 2026

Why Mac Steam won’t run Windows games on its own

Steam on macOS knows about every game you own, including the ones that only ship for Windows. Without a Mac build there is nothing for it to run, so those games stay greyed out or uninstallable.

On Linux, Valve solves the same problem with Steam Play and Proton. Valve describes Proton as “a tool for use with the Steam client which allows games which are exclusive to Windows to run on the Linux operating system,” and you turn it on in the Steam Play section of Steam’s settings.^[1] In Mac Steam, the same Steam Play code is present but switched off.^[2]

Where the in-Steam approach comes from: NotProton

Bridgeplay takes the idea of running Windows games inside the Mac Steam client from NotProton. Its README says that it “enables the Steam Play experience from Linux Steam in the macOS Steam client” by “forcibly enabling the Steam Play functionality in macOS Steam (which is present and inert),” and runs games through CodeWeavers’ CrossOver.^[2]

Bridgeplay is a fork of NotProton by way of Leon Seemann’s NotProton-WineHQ. The Steam hooks, the Steam Play interface patches, the run script and the steamclient bridge all started as NotProton’s work.^[3] NotProton in turn credits earlier projects, among them Nat Brown’s Kaon, mont127’s Neutron and Gio’s work on Steam Play in Mac Steam.^[3]

How Bridgeplay does it

Bridgeplay copies a small library into /Applications/Steam.app, makes Steam load it at startup, and re-signs Steam on your Mac. The library hooks Steam’s compatibility tool, shortcut and launch option code and shows the Steam Play settings. Bridgeplay’s tools go in Steam’s compatibilitytools.d folder and become Steam’s default compatibility tool.^[3]

When you press Play, the game runs in CodeWeavers’ open-source WineCX engine under Rosetta 2, with Apple’s D3DMetal for DirectX 11 and 12 and DXMT or DXVK as alternatives. Steam calls from the game reach your Mac Steam through Proton’s lsteamclient. How the pieces fit covers the rest of the chain.

If a game has both a Mac and a Windows version, Steam downloads the Mac one unless you force a compatibility tool for that game.^[2]

Setting it up

1. Download Bridgeplay and drag it into Applications.
2. Follow the Setup Assistant. It installs Rosetta, fetches Apple’s graphics components (and Steam from Valve if it’s missing), asks you to sign in to Steam and walks you through the macOS permission prompts.
3. Install a Windows game from your Steam library and press Play.

The install guide covers each step and what to do if one fails.

Per-game settings live in Steam

Each game’s Bridgeplay settings are in its Steam Properties: right-click the game, choose Properties…, then Bridgeplay. That page holds the graphics backend, the Metal HUD, DLSS (answered by Apple’s MetalFX), frame generation and controller options.^[3] Some games also get default fixes from Bridgeplay’s gamefix files, such as skipping a launcher that crashes under Wine.

What works and what doesn’t

Compatibility results are reports from players and maintainer tests, not guarantees. Bridgeplay is experimental software.

The Steam Subscriber Agreement caveat

Bridgeplay changes your Steam app and replaces Valve’s signature with a local one. Valve doesn’t support or endorse Bridgeplay, and modifying Steam may go against the Steam Subscriber Agreement.^{[3] [4]} Use it at your own risk. Repair Steam or Remove Everything on Bridgeplay’s Status page restores Steam’s Info.plist; if Valve’s signature doesn’t come back, reinstall Steam from Valve.

Other ways to run Windows Steam on a Mac

The usual alternative is to install the Windows version of Steam inside a Wine bottle. You then have two Steam clients, but the Mac one stays untouched, and these tools also handle other stores.

Bridgeplay fits if you are on macOS 26 or later, play mostly Steam games and want them in the Mac Steam library you already use. If you’re on macOS 14 or 15, buy games on GOG or Epic, or don’t want your Steam app modified, one of the tools above is the better choice. The overview of every way to play Windows games on a Mac compares them in more detail.