Wii U emulator on Batocera is CEmu, a Windows binary that runs through the wine Windows compatibility layer on Batocera.

You can use the following WiiU ROM formats:

• wud: a single file, which is a direct physical game dump.
• wux: single-file compressed versions of .wud dumps.
• Loadiine: a directory structure with multiple files and folders, usually shared as a .rar archive. You must unfold the archive as a directory structure in roms/wiiu/. This format is a decrypted version of .wud dumps. Batocera will use the [game].rpx binary file in the /code/ directory structure of the Loadiine unarchived ROM to launch the game.

You also need a text file named keys.txt. This file needs to go in the bios/cemu/ folder. If you have a pop-up window telling you “Error in keys.txt line XX”, it might be because your keys.txt file is not correctly located in /userdata/bios/cemu/.

This keys.txt is a plain text file containing several lines, one for the common Wii U key, plus one for each game you want to support. # is used for comments. Google is your friend if you want a Wii U keys.txt pre-filled with many games.

CEmu WiiU emulator works best with Vulkan drivers if your GPU can support it. You can tweak the graphic options from the CEmu-config application that is launched from the Batocera menu application (press [F1] on your keyboard, from the main systems menu in EmulationStation).