I know the guy that made this hack, he has made many for the Nintendo Entertainment System - he updated the classic Nintendo Pro Wrestling with rosters for WWE, Impact Wrestling, and I believe AEW. He certainly has more time on his hands than I do, lol. I could not even begin to figure out how to change the graphics and such in a NES game and here he is taking one game and makes a new one.
He does this with a lot of NES games which is quite cool.
RE: God of War on NES Game Hack