Annotated chess game

Just as my previous annotated game, this is not really a game either. This is actually a puzzle by John Nunn (one of the best helpmates in my opinion!). The puzzle goes as simple as follows: "A game starts with 1. e4 and ends on the fifth move with knight takes rook checkmate" (Note that the puzzle does not state which side mates which!!). "Simple" might be a bit exaggerated though... :-) Even Mr Kasparov himself was unable to solve it! If you haven't heard it yet, take a couple of minutes (or rather a couple of weeks like I did) and try to solve it yourself. It's really worthwhile!!