Horus Menhoset IX appears in game when you are on Ava Cadavra's task to find a pyramid in the desert. He will eventually help you smash the Bovine Shrine and replace it with the statue of an Egyptian god. You will need to stock up on gourds and sacrifice them to the statue in order to keep Horus from a trance state where he won't move or talk to you.
Game Boy AdvanceEdit
In this version of the game he is just called "The Mummy". He has his own pyramid that is called "The Ziggurat" which is infested by TseTse flies. He is very lonely and steals items from people to see if those things make him more happy. He even kidnaps Penelope Redd and is somewhat hard to intimidate.
His secret is that he has established a profitable online gift-wrapping service.