We need a Killer King achievement please.
Since discovered checks count for the respective piece, a checkmate by a king move would be possible (I have even seen O-O# and O-O-O# already). That is definitely achievement worthy IMO.
Oh thank you very much; Didn't realise because unlike the others, these 2 are actually hidden. So, since the others were visible I assumed that the King doesn't exist. Very Helpful.