Hint: Sacrifice then manuver to a mate
Hard Puzzle
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Isn't 18. Bc4 a mate?
Indeed this is hard due to your absurd and bad moves.
That is true it would work with 18.Bc4. However, that wouldn't be how the game went
But in puzzle usually it follows the "best play" of both sides.
You should have saved this as a game, not as a puzzle. A puzzle shouldn't be more than five moves. Also, that wasn't much of a hint considering that you sacrificed within the first two moves and did not have mate for a while. 
Lengthy puzzle. I think you should have posted as a shared game if you wanted to boast about your protracted and self-perceived ingenious checkmates.
PAWN ASSASSIN!!!!