Movies are much like video games in that studios often spend a large amount of money on projects that may seem promising but never see the light of day. There was once a Superman film, starring Nic Cage, written by Kevin Smith, and directed by Tim Burton that seemed to make it at least moderately far in pre-production before it was canned.
The documentary The Death of Superman Lives takes a look at the doomed production, and the film's first trailer is amazing, featuring camera tests with a strange-looking Nic Cage, a Superman suit that included plastic armor and a strange lightning effect. The whole thing seems deeply, deeply bizarre.
The movie went through many changes and different artists and writers took a crack at the project, so it's a little misleading to think of the project as a single entity. Big franchise films often go through large changes, and teams of writers take a crack at the script through the years these films often spend before the cameras roll. Kevin Smith has talked about his experiences writing the script in detail, and it's a hilarious look at how maddening Hollywood can be for creatives.
The documentary is now in its second crowdfunding effort to raise funds needed to finish, and it looks like the final product will be amazing. This joins Jodorowski's Dune as recent documentaries that dig deep into movies that were never made, but sound incredible. There's a world of work between "these ideas were interesting" and "this finished film is great," so we're judging work by what might have been, but it's still fascinating to see what might have been.