The king, trapped by its own pawns
The castled king sits behind its own pawns, safe until the back rank goes undefended. Then a rook or queen slides in for mate.
Knight checks. The king has only one legal square.
3 more clean runs (at any point) to reach Recall.
King boxed in by its own pawns. Back rank is the target.
3 more clean runs (at any point) to reach Recall.