A WUX file is the compressed version of a Wii U Disk Image WUD file. It is generated using the Wii U image compression tool to reduce the file size of WUD segmented files which are around 20 GB in size otherwise. This much large size game information files are reduced to around 2 GB in compressed WUX files that makes file transfer easier. WUX files can be opened and played with video game emulators such as Cemu.
WUX File Format
WUX files are saved as compressed files that can be decompressed for loading in emulators using the Wii U image compression tool. The Cemu video game emulator can also load the WUX files and load the complete video game information.