Movies with Weird Gimmicks

A list of movies that shoot for the stars, trying to make films with all sorts of strange and inventive gimmicks. They don't always succeed, but they most definitely have a good hand in advancing cinema through their efforts.

Movies that are extremely weird thanks to any narrative, editing, camera, etc gimmicks are certainly welcome here. Experimental, but without the "this is kinda incomprehensible" stigma that comes attached with that label. Some of these are actually very conventional movies, just with certain gimmicks involved. So there's no specification here.

If there are a few films with the same gimmicks, that's fine, as long as that gimmick didn't become super popular (i.e. Blair Witch Project, This is Spinal Tap, Roger Rabbit,…