Ensure your console has the latest sigpatches installed. Without these, the Switch will fail to launch custom NSPs.
FUSER's official multiplayer servers were shut down in December 2022, so the single-player campaign and freestyle modes will be the primary functional components. FUSER-NSP-ROMSLAB.rar
The .rar file is a container. Use a tool like or WinRAR to extract the contents. Ensure your console has the latest sigpatches installed
You should find one or more .nsp files inside, which are the actual game or update packages. 2. Choose an Installation Method install the Base Game first
If the .rar contains multiple files, install the Base Game first, followed by any Updates and then DLC.