How about 1.e4 Nf6 2.Qe2 (2.f3) 2...Nxe4 3.f3 (3.Qe2) 3....Ng3 4.Qxe7+ Qxe7+ 5.Kf2 Nxh1#.



Pity about the dual on move 2. Otherwise, a nice problem.

It took me awhile to solve this. I solved in my head during slow points at work, but finally got it at home (using a board sure helps!). I'd say an hour or two of total thought.

I'm not surprised that it stumped GM's. They are not trained to think this way at all. For them, White and Black will always be opponents. In this type of problem, White and Black must cooperate to achieve the goal.

A similar example is http://www.chessatwork.com/board/showthread.php?threadid=19565.

In a Proof Game, the final position is given to you. A good example is:



Position after Black's 4th move. How did the game go?
a) diagram
b) remove Black's Queen

Just laid my eyes on a beautiful problem and not too complicated at that: Mate in 1

EDITED: FEN problems

You're missing the point. You have to deduce whose move it is.

This is known as a parity problem. The structure is such that neither side can lose tempo, so I can say that White has made an odd number of moves and black has made an even number of moves. Parity is different, which only happens after white has moved. Therefore, it is black's turn, and the answer is 1...Nxc2#.