Settings

MULLION_LOG_PATH=<folder>	Writes a log for each DLL into the folder. Attach the logs to a bug report.
MULLION_D3D12_METAL4=0	Keeps Direct3D 12 on Metal 3. If a game draws differently on Metal 4, please report it.
MULLION_CONFIG="dxgi.customVendorId=106b"	Reports Apple's vendor ID. By default Mullion reports the GPU's name with AMD's vendor ID, because some games exit when they do not know the vendor.

Options can also go in a mullion.conf next to the game's executable, or in the file MULLION_CONFIG_FILE names. mullion.conf lists them, and DEBUGGING.md covers the logs and other diagnostics. The DXMT_ names and dxmt.conf of earlier versions still work.