How Grapple works

The short version

When you press Play, three layers do the work, and Grapple includes all of them:

• Rosetta 2 runs the game's Intel (x86) code on your Apple chip.
• Wine answers everything the game asks of Windows — files, windows, sound, controllers — with the macOS equivalent.
• A graphics layer turns the game's DirectX calls into Metal, the graphics your Mac speaks.

There's no Windows inside and nothing is emulated, so there's no Windows licence to buy and no virtual machine slowing things down.

The CPU: Rosetta 2

Windows games are built for Intel and AMD chips. Rosetta 2, the translator built into macOS, turns that code into Apple Silicon code as the game runs — the same thing that ran Intel Mac apps on the first M1 Macs. macOS offers to install it the first time Grapple needs it.

Grapple leaves AVX, a set of CPU instructions some newer games insist on, switched on for every game, so those games get it whenever your version of macOS offers it.

Windows: Wine

Wine is the long-running open-source project that makes Windows programs run on other systems. It replaces Windows' own libraries with versions that call macOS instead. Almost every way of running Windows games on a Mac or on Linux is built on it, including Valve's Proton on the Steam Deck — which is why “works on Proton” is a useful hint for Macs too.

Grapple's engine, grapple-wine, is Wine 11.0 with our own fixes for the things we ran into on Macs. A few examples:

• Steam draws its window. On some Macs the Windows Steam client opened as a black rectangle; the engine fixes how Steam's interface is drawn.
• One Dock icon per launcher, with its own name. Launchers run as several processes, which used to fill the Dock with icons called “wine” or “steamwebhelper.exe”.
• Epic can install games. The Epic Games Launcher prepares each install folder through a helper that reports back by writing to a folder. Wine on macOS never noticed that folder change, so every install failed with “you do not have permission to install”. The engine now watches for it.

msync is on by default: a Mac-specific way for Wine to handle a game's threads waiting on each other, which mostly helps games that lean on the CPU.

Graphics: DirectX to Metal

Windows games draw through Microsoft's DirectX (Direct3D), versions 9 to 12. Macs only speak Apple's Metal, so every frame goes through a translator. There are several, each with strengths, and Grapple includes four:

You don't have to pick: games start on D3DMetal, and older ones fall back to WineD3D by themselves. If a game misbehaves, its settings in Grapple let you try another layer. That setting belongs to the Windows environment the game runs in, so it applies to the other games from the same store too. Launchers get what they need without you asking: Epic's launcher draws its window with DXVK, while the games it starts use your environment's layer.

The DirectX guide goes deeper into each layer, including VKD3D-Proton, Linux's DirectX 12 layer, and why it isn't practical on a Mac.

One Windows environment per store

Each store gets its own Windows environment: a separate C: drive with its own settings. Steam, the Epic Games Launcher, GOG Galaxy and games you add yourself never share one, so a launcher update or a game's installer can't break the others. Grapple creates them for you; you just see your games, grouped by where they came from.

What Grapple downloads

The first time you open it, Grapple downloads its engine and D3DMetal — about 250 MB together — and checks every file against a published checksum before installing it. Everything stays inside Grapple: there's no Homebrew, no Terminal and no developer account involved.

grapple-wine is open source under Wine's licence, and its full source code, including our fixes, is on our open-source page.

What can't be translated

• Kernel-level anti-cheat. Valorant, Fortnite and many competitive shooters install a driver into Windows itself. Wine can't load Windows drivers, so those games won't run — see anti-cheat games on a Mac.
• Windows drivers in general, and VR.
• Your Mac's graphics power. Translation costs a little, and the graphics in a base M-series chip are modest, so big recent 3D games want lower settings there.

FAQ