GPTK4 Launcher

A small macOS launcher that automates setting up Apple Game Porting Toolkit 4 (DirectX 12 → Metal 4 translation) with CrossOver, so you don't have to do the manual file-copying and config editing every time.

It automates the workflow from the setup video:

1. Duplicates CrossOver.app → CrossOver GPTK4.app (your stock CrossOver is never touched).
2. Mounts the GPTK4 Evaluation Environment disk image and swaps its redistributable/lib folders into the duplicate's Contents/SharedSupport/CrossOver/lib64/apple_gptk (originals are kept as *.backup).
3. Copies the NVIDIA DLSS shim into the Steam bottle's windows/system32 (nvngx_on_metal.dll is renamed to nvngx.dll).
4. Adds the config keys to the bottle's cxbottle.conf:
   • "D3DM_MTL4" = "1" — enables the Metal 4 backend
   • "MTL_HUD_ENABLED" = "1" — Metal performance HUD (shows D3D12 (Metal 4) in-game)
   • "D3DM_MAX_FPS" — optional frame-rate cap
5. Launches Steam through the patched CrossOver.

Prerequisites (one-time, manual)

These can't be automated because they need your logins/licenses:

Step	What to do
macOS 27.0 "Golden Gate" beta	Required for the Metal 4 translation layer
Apple Developer account	Register your Apple ID for free, then download the GPTK 4 Evaluation Environment DMG into ~/Downloads
CrossOver (26.1+)	Install to /Applications and activate your license or trial
Steam bottle	In CrossOver: Install → Steam, click through the installers, log in to Steam once, then quit
Bottle toggles	In the Steam bottle's settings, turn D3DMetal and DLSS ON

Easiest way: the GUI

No Terminal needed:

1. Double-click Create App.command once. This builds GPTK4 Launcher.app in your Applications folder.
2. Open GPTK4 Launcher from Launchpad or Spotlight. You'll get a simple menu:
   • 🎮 Launch Steam (Metal 4) — starts Steam through the patched CrossOver
   • 🛠 Set up GPTK4 — does the whole setup with normal Mac dialogs (it finds the downloaded disk image automatically, or lets you pick it)
   • ✅ Check my setup — tells you what's missing, in plain language
   • ↩️ Restore original CrossOver — undoes the setup

If something goes wrong, the error dialog has a View Log button (the log lives at ~/Library/Logs/gptk4-launcher.log).

First time macOS may block the .command file: right-click it → Open → Open.

You can also skip building the app and just double-click GPTK4 Launcher.command — it opens the same menu.

Command-line usage

./gptk4 check                  # verify everything is in place
./gptk4 setup                  # patch everything (finds the DMG in ~/Downloads)
./gptk4 setup /path/to/Evaluation_Environment.dmg   # or pass the DMG explicitly
./gptk4 launch                 # start Steam through CrossOver GPTK4
./gptk4 restore                # put the original CrossOver libraries back

Configuration

Edit the variables at the top of gptk4, or use environment variables:

• GPTK4_BOTTLE — bottle name if yours isn't called Steam
• GPTK4_MAX_FPS — e.g. GPTK4_MAX_FPS=60 ./gptk4 setup to cap frame rate (saves battery)

Notes

• Only DirectX 12 games go through the Metal 4 layer; the HUD in the top-right of a game will read D3D12 (Metal 4) when it's active.
• Re-running setup is safe: backups are only made once, and config keys are updated rather than duplicated.
• restore undoes the library swap inside CrossOver GPTK4.app if a CrossOver update or a new GPTK build misbehaves.