make an open world Diablo clone (that uses robots)
Holy hell great idea.
Crazy cyberpunk robots just rushing the shit out of you as you fight them off with lasers and bombs.
It sounds like a crazy idea until you start to think about it. Using robots removes all sorts of stupid self-imposed limitations. Everything from character design, weapons, armor, and violence (no more blood and gore to worry about) along with the fact that since your robots are already doing large amounts of violence you can justify anything else you want to put into the world.
WWII was used by every game designer imaginable, then zombies became popular. I'm gonna make the claim right now: robots will be next.