I've always liked the idea of time travel as a mechanic in video games and i thought of a game where you go back in time to save the future. The game would be a roguelike and you would reset every time you die. You would travel through different time periods and have to fight like cavemen or something and then you'd fight your way through some ancient civilization like Mesopotamia or something then you would go through the Roman empire and then you would be in the middle ages. Then you would go through the Renaissance after that would be like WW1 or 2. Then it would be modern day. And finally there would be some dystopian future. Each era you would have to complete some kind of objective so that you are able to fight the final boss (i.e. destroy some painting that would influence the dystopian future) but during each era you would collect some artifact or something that changes the way you play going forward like you would get something that makes it so you can't dodge roll anymore and instead you would do a pary or something. Idk just an idea I had