The full source code for Pokémon Gold Version and Pokémon Silver Version has been shared online, and fans have been thoroughly enjoying going through the dozens of images that were part of the various builds. This includes pictures of front and back Pokémon sprites and beta designs for characters such as Pichu and Shuckle.
https://www.notebookcheck.net/Huge-Pokemon-Gold-and-Silver-source-code-leak-reveals-some-very-beta-looking-pocket-monsters.462921.0.html
Harry Potter had such potential, but AFAIK all mobile games using the IP are money grabbers.