Ghostbusters
Dan Aykroyd’s original idea for Ghostbusters, or “Ghost Smashers” as he called it, is quite a trip to read. Some things are the same, like the Ghostbusters living in a firehouse and using proton packs, but then they’re also battling ghosts across dimensions and space. Yeah, things go a lot further than New York City in this original vision, which, weirdly enough, still featured a cameo from the Stay Puft Marshmallow Man.
Article source: https://www.cinemablend.com/news/2547807/star-wars-and-5-other-major-franchises-that-drastically-changed-direction-during-scripting