In the early 20th century, musicals were theater productions. In the early 21st century, superheroes lived mainly in comic books. Both managed to make the leap into the medium of film, with a few stumbles on the journey, and they wound up creating entirely new film genres in the process.
The creations of the two film genres mirrored each other, and both can offer lessons to anyone wondering how a genre changes when it successfully switches mediums. In other words: Video game movie producers, start taking notes now.