The Wii does not natively support loading games from USB or SD card. However, through homebrew and USB loaders , you can play backups of your legally owned discs. These loaders expect a specific folder and naming structure on your storage device.
RMGE01.wbfs RMGE01.wbf1 Use Wii Backup Manager (Windows) or wit (command line) to convert ISO images to .wbfs files. wii backup file system
wbfs Inside wbfs , each game should be in its own folder, or the .wbfs file can sit directly inside wbfs (less common). The recommended modern structure is: The Wii does not natively support loading games