A regular game has been played where White still has all 16 pieces. White promoted only a single pawn, and not to queen. In the final position all 16 pieces of White have (at least) one mating move. Yes, also the king. Find the position. ("The"=it is mostly determined, allowing for variations)
Yes, fitting for Silvester there is a little gag hidden, but it is entirely conforming to FIDE rules.