+p.
+ When the king is under check, a legal orthodox move must be played.
+ Some weird situations would occur otherwise, like on the following diagram.
+ If we allow self-(re)captures then the king would take on h2 and escape to
+ the third rank.
+
+figure.diagram-container
+ .diagram
+ | fen:7k/8/8/3QR3/3P4/4P3/r6P/q6K:
+ figcaption 1.Kxh2 by anticipation isn't allowed: white is checkmated.
+