An interesting aspect of the pawn movement is that a pawn on a semicircular square can capture, but not be captured by, a pawn on the semicircular square directly rimwards. In normal chess, all threats between equivalent pieces are mutual. (Well, except for the en passent rule.)

I think I agree with the others saying pawn movement is hacky. I'd be inclined to say that a pawn promotes when it reaches either side of the board, but this isn't great because you need to keep track of where a pawn started to know which direction it's going.