How Koga decides
Absolute A knight delivers checkmate
- Smothered mate is a special kind of checkmate. It is only flagged once the position is genuine checkmate — the king is in check and has no legal reply at all.
- The piece (or pieces) giving that final check must be a knight. A knight cannot be blocked, so a king with no flight squares has no answer to a knight check.
Smothered The king is boxed in by its own army
- Every square next to the mated king must be occupied by one of the king's OWN pieces — its rooks, pawns, bishops and so on.
- Because the king is hemmed in on all sides by friendly pieces, it has nowhere to run when the knight checks. The king is smothered.
- If even one neighbouring square is empty or holds an enemy piece, it is an ordinary checkmate, not a smothered mate.
Roles Smothered mate replaces plain checkmate
- When a forcing line ends in mate, Koga adds the mating motif as the headline pattern. If it recognises the smothered shape it labels the finish 'smothered mate' instead of plain 'checkmate'.
- Everything that set the mate up — a queen sacrifice, a discovered or double check, a deflection — is kept on the board but demoted to a supporting role. The smothered mate is the point of the combination.
Test positions (the examples that guard against regressions)
Classic smothered mate (Nf2#)
Lichess 01TmZ. The famous smothering pattern: Nh3+ Kh1 Qg1+ Rxg1 Nf2#. After the queen sacrifice draws the rook to g1, the knight lands on f2 with check. The white king on h1 is hemmed in by its own rook on g1 and pawns on g2 and h2, so it cannot escape the knight's check — mate.
Attacking piece
King
Escape / key square