Black to move - Mate in 1


Bro nb6# cz the whites pawn can't take they are in the last promotion square in this puzzle

I made a graphic solution:-)
This game is from a mirror universe.
I made a pic of the solution but deleted it, or it would no longer be a puzzle.

it's not a checkmate, a7 or c7 pawn can still eat the black knight
see the first comment
I prefer a version where the White pieces are all on the squares the similar Black pieces are on (Ke8, Qd8) and Black only has a King on e1 and a Knight on c3.
Then you can offer to play somebody where they pick the side to play as long as you get the first move (i.e. whoever moves first wins).
If Black moves first then 1 ... Ne4 and 2 ... Nd6#
If White moves first then 1 Nf6 Nb5 2 Ne4 (covering both f6 and d6) and 3 g1=Q, 4 Qg6 followed by normal moves (with a N+2Q+2R+2B+7P advantage) now that the mate threat has been stopped
One advantage of that version is that it is a position that can be reached in an actual game. The OP's version cannot because the pawns cannot pass through each other.