In a casual chess game I had, my last move was to promote a pawn in the back rank, to ladder mate my opponent (there was already a rook on the 7th). I moved the pawn, but while I was grabbing for the queen piece I ran out of time. Who won?
In tournament rules, if the allotted time runs out, you lose, unless you checkmate or stalemate. In this case, the move immediately ends the game.
In this case, there are two possibilities: if the queen had touched the promotion square, then the choice is final and the move is technically played, therefore you win. If the queen didn't touch the square, then you could have changed your mind and chosen any other piece, which might not give mate, therefore you should lose on time.
If you ran out of time, there are still cases where the game is drawn due to a lack of possible checkmates.