Fastest mate possible for this situation? This one is a little tricky, and requires some out-of-the-box thinking. Try to solve it without looking at the hint.

Hint (highlight text): Sometimes it helps to look at it from another point of view. The fastest solution is simpler than you think.

This is one of my favorite puzzles... and you will see why when I release the answer. :)

Did white initially begin playing on the bottom side or top side?

I just take a quick look of the game. I don't see any quick mates. It seems to me black piece has an edge in a game. The game is not a closed match. It is hard to compete if one side has a rook up with that position. 

Bottom, promote and win.

This is true. I did not expect someone to solve it this quickly. Congratulations.

I am assuming white piece is playing at the top side.

Hey danjr, if you can post on chess.com like that, I can pull the FEN and put in game editor (I did to make sure). Enforcing legal moves or showing board coordinates in the Game Editor (More -> Game Editor) would kind of give it away.

I never use Game Editor, so I did not realize that. That kind of ruined it, huh?

If White started from the bottom, then really Black can promote first and mate White immediately...

@danjr - No, I've seen too many puzzles using that, en passant, and castling as key moves.

@arceus03 - it's white to move and I think white wins.

Oh wait - black wins by promoting to a queen on his first move. Not finding a way around that.

It's a trick: Black wins.

Exactly.

You can even simply promote to a Bishop, if White doesn't move his King :P

Sorry, I actually meant it to be black to move... I will change that right now.