Genesis Plus GX WAD is a "forwarder channel" for the Nintendo Wii that allows you to launch the Genesis Plus GX emulator directly from the Wii System Menu. While the emulator itself is the engine, the WAD serves as the visual shortcut, making your homebrew setup feel more like a native console experience. Genesis Plus GX Overview
If you meant something else — like a .wad ROM hack or a different platform — please clarify. genesis plus gx wad