If you can't figure out how to take something change it without breaking the fun then you're most likely doing a rip-off.

You have to do something transformative for it to not be a rip-off. Just add an example, if you take Hollow Knight gameplay and then make a game with art style heavily inspired by Hollow Knight art and your story is about some other bugs, then that's pretty much just Hollow knight and as such would be a rip off. But if you took Hollow Knight gameplay and made it about robots in a space derelict that could be transformative enough to be its own thing.