I mean, I don’t know about “open world” being a good idea, but a crazy taxi take on Fall Guys would be pretty amazing. Throw 99+ people into various scenarios, all behind their own taxi, could have a lot of crazy outcomes. They just need to find the right balance for shenanigans and they’d have a solid multiplayer hit.
Trying more than a structured arcade-style approach would probably hamstring those efforts though; it ain’t GTAV.