What is a RPX file?
An RPX file is a game file that can be loaded or played by the Wii U game console. It can also be loaded and played in the Cemu video game emulator that is popular for providing emulator environment for Wii U files. Wii U game files are large in size and can also be saved as WUD or WUX files for loading by game emulators. An RPX file contains the entire executable game that comprises of all the game components such as graphics, textures, sequences, and the game ROM.
RPX File Format - More Information
RPX files are saved to disc in proprietary file format. Certain APIs are available to compress or decompress RPX files such as wiiurpxtool. Moreover, applications such as Cemu video game emulator lets you play Wii U games in Windows on PC.