Shrink-chess

White to move, mate in 1
(a chess diagram you cannot see for some reason)
A mate in 1? How hard can it be

Did you find it? A mate in 1. The answer is: simply promote your pawn to queen. Mate!
(a chess diagram you cannot see for some reason)
Why is it mate? Well, if you would try to take the queen with the knight on d3, then the 3rd row would shrink, and the kings would be adjacent - which is not allowed.
Then, you might think that you can take the queen with your king. However, the queen is clearly covered by the bishop! For, if you would take the queen, then the second row would shrink away, and the bishop would attack the king.
No other move removes the king from check, so that's the definition of mate.