Haunt

About

Haunt is a cancelled spin-off game in the Mario series based around Boo. The game was set to follow the story of a young Boo after he graduates from Haunt university.

Not much is known about the game, but it's existence was discovered in 2020 when concept art for the game was discovered on the online portfolio of Sammy Hall, a former concept artist for Retro Studios.

Source: IGDB