He appears to be a normal-looking Goofy costume without his head and some discoloration around the body. His head is the same as his Disney counterpart as well, with the exception being that it has no long, droopy ears. Acephalous also wears a yellow jacket unlike Goofy's original black one.
The game's creator, Matthew, has confirmed that Acephalous's body will be hostile while his head is not, but the head will still move. Matthew also confirmed that Acephalous's head will act like Pluto and Disembodied, attracting the other suits into The Office.