The Mario movie we ended up with in 1993 was nothing like the games it was based on. An earlier draft for the film, however, was a lot more faithful.
It's impossible to tell whether it would have been any good, of course, but in sticking to the basics of the Mushroom Kingdom it at least couldn't have been any worse than the flick Bob Hoskins and Dennis Hopper bumbled their way through.
Two years before the final product was released (so in 1991), a script for a Mario Bros. movie was written by Jim Jennewein & Tom S. Parker. A pair with a long history of collaboration, they've worked together on movies like The Flintstones and Major League.
Their idea for a Mario movie was one rooted in Nintendo's video game franchise, though also bearing the more "realistic" influences we'd see in the eventual screenplay. The story goes like this: a pair of plumbers in modern-day Brooklyn, Mario and Luigi, are dragged into a fantasy conflict when Luigi's crush (Hildy, the cute girl at the local florist) is abducted by a mysterious man named Koopa.
Chasing after her, they find a restaurant with a mysterious pipe out back, and upon investigating are sucked into a fantasy land, dropped onto a green, grassy plain where they're immediately attacked by piranha plants. Linking up with Toad and Yoshi (who was called "Junior" for some reason), they lead the fight against Koopa's forces, culminating in a "boss fight" between Mario and Koopa.
What's appealing about this initial screenplay is how much more faithful it is to the source material. Koopa (or Bowser) is a giant lizard. Toad is a small, mushroom-shaped creature. Yoshi is a dinosaur. Koopa flies around in a giant floating pirate ship. Even the climactic boss fight ends over a pit of lava, just like the original Mario games.
Why, then, was it discarded? Who knows. A good guess, though, would be cost, as in the early 1990s the special effects required to bring all those characters to life (in addition to creating all the fantastical sets) may well have been prohibitive for a movie of that scale.
It wasn't the first script to be turned down for the project, either. The Mario movie went through a number of reboots and re-writes, with screenplays submitted inspired by movies like Ghostbusters (a team-based comedy), Die Hard (complete with Bruce Willis cameo) and Mad Max, the latter of which, with desert races and a very adult tone, was apparently so good it convinced Hoskins and Hopper to take part in the project.
After which they were promptly handed an all-new script, one which was nothing like the one they'd signed on for.
If you've got the spare time, all these scripts are available in their entirety from The Super Mario Bros. Movie Archive, where you can also get some summaries of each film's plot should you be a little more rushed for time.