Here we have an easier but still interesting selfmate in 5.
This is a puzzle by A. Rubin found in The Book of Extraordinary Chess Puzzles:
From the book: "In a 'selfmate' problem White plays to force Black to checkmate him - a sort of chess suicide. In the diagram above, White has his king nicely trapped in the bottom right-hand corner, but still has to find a way of forcing Black to deliver the mate. Selfmate in five.