>>60553310 (OP)look at schedule 1 that's made millions. Forgot 2d sidescrollers and all that you can't get rich off those. Build a 3d game with simple style graphics, ad focus on a fun game loop, something not too intense. Schedule 1 has that, he also streams whilst he codes, so people saw the game from super early.
I'd say if you're building something now, build a "job simulator", something that scratches part of the GTA itch. Maybe a game about running a mafia crew, or a game about stealing cars or running a chop shop.
Use premade assets initially for animations and models. change them later after you have a fun game loop.