Modding New Ghostbusters II into a game based on Afterlife.

I was daydreaming the other day and thought came to me: how much work would it take to modify/Rom hack New Ghostbusters II on the NES?

Nintendo Entertainment System games use a tile based system for graphics and are coded in assembly. in theory how much work would create new pixel art tile sets to represent the farm, Summerville, the mine etc and it to add/replace the guys’ sprites with ones of Phoebe, Trevor, Podcast and Lucky? The ghosts would have to be replaced too. Off the top of my head you could use Muncher, bug eyed ghost, terror dogs, zombie miner and Gozer

I came across this tutorial that should help you out.

Hope you have a lot of patience.

I wonder if I could get someone to do chibi style artwork of the afterlife protagonists so I’d have something to work from?