3.Qg6ch Kf8 4.Re8 checkmate:)
After Kf8, why not Re8#?
Doesn't 3.Qg6+ lead to the exact position after the 4th move?
Alright, for all you smart people out there, I fixed it. Mate in 4, though I don't know how to edit a title...
Multiple solutions! For one, 3.Re7+ is also a mate in four.
"Mate in 6" is still a great title!