Originally posted by SwissGambit
Helpmate in 3
In a helpmate, Black moves first. The players move collaboratively. White's 3rd move should checkmate Black.
Here it goes:
1.Rf1 (Pass the "critical square" f2) Rxe7 2.Bf2 (so the bishop can block the rook and enable...) Ke5 3.Ke3 Kf5 (...this)#
1.Bg1 (Pass the "critical square" f2) Bxc6 2.Rf2 (so the rook can block the bishop and enable...) Kd5+ 3.Kf3 Kxc5 (...this)#
Which is, I believe, a double implementation of the good old Indian Theme in an helpmate ( "Hilfsmatt-Inder" ).
Note how all 6 moves is one solution parallel the corresponding moves in the other solution: Bs and Rs swap their jobs.