This idea has been sticking in my mind for quite some time now and I'm honestly not a good writer, as well as a lazy guy who likes to read, and only read.
My idea, which is not really fresh for some, works like this.
The MC which is from conventional universe's Earth, reincarnated as a newborn in a dimension that appear to it's inhabitants and especially the MC, as a normal world similar to Earth.
In reality, the inhabitants of that world couldn't perform anything beyond human limit on their own world or dimension. BUT, outside of their dimension, they're literally the most powerful, unequally so, beings. Too strong that their mere existence could shatter the reality, space, and time rules of lower dimensions.
I like the concept of worlds classified into tiers, and the very nature of the MC new world exceed anything and everything that exist in the Infinite space(which house worlds, universes, Omniverses, and more). MCs new home world somehow exist beyond the infinite space.
I entertain the idea of the MC becoming Systems creator as well, and the peoples and characters he gave his system to, would add a degree of color and entertainment. That, I believe.
That said, this idea is very broad and could be made into many fanfics or new novels. Or, a long ass novel that mixed a lot of elements from existing works such as Marvel, DC, animes, Harry Potter, or anything, etc., etc.,
It's best if the MC is not always horny guy that catch females characters like pokemon or something. Make him a little bit of a manipulative sort, maybe? A sociopath? Thought it'd make the story gooder that good.
Note : Hit me up if you guys wrote new works so I can read them. XD