AAA game engines are really challenging, nowadays you are expected to process everything on GPU. You need to do realtime illumination and collisions in a very p

AAA game engines are really challenging, nowadays you are expected to process everything on GPU. You need to do realtime illumination and collisions in a very performant way. If you can do that, then you might have a chance to compete against industry beasts like Unreal. Otherwise your best chance is creating a "game maker". A framework with editor that allows people to make simple to medium complexity games easily but won't require high performance. There are a lot of low skilled gamedevs that would love it. The decent money could come from services you offer around the engine.