Deductive giant killer

I blatantly ripped this one off from chessbase.com, where they said it stumped many Grandmasters, including the great Garry Kasparov. It's a very simple puzzle, which makes it all the more interesting. Here we go:

A game begins 1. e4 and ends in the 5th move with knight takes rook mate. What was the rest of the game?

This puzzle was killing me a few years ago, I couldn't find the answer on-line, and I couldn't figure it out. I assure you it is possible, it isn't a trick question; I eventually solved it quite randomly in the middle of taking a shower; go figure.

I ask that any answer submissions be in white so that if you're right, you won't spoil it for everyone else.

I couldn't find the solution, but I found one that ends in the 6th move with knight takes rook mate:

1. e4 f6 2. Nf3 d6 3. Nh4 Bf5 4. exf5 Kf7 5. Ng6 Qe8 6. Nxh8#

That seems to be ok for a mate in 6 with NxR# (although I haven't really checked it). However, we're clearly looking for it to happen in the 5th move. I remember that I found oh, maybe half a dozen distinct mates in the sixth like this before finally getting the solution.

But what about the people with non-white backgrounds? :P

If you can figure out a way for it to be invisible to everybody, please suggest it. I'm just not seeing any better alternatives to white text, considering that most people do have white backgrounds

we could just pm u instead of writing with white letters in the forum.

Or at this point you can just check against PurplePuppy, who got it right this time