Complex moves
Ten positions. Each one isolates a rule that casual boards skip: castling through check, the ghost capture, the underpromotion, the pin.
Tuck the king and bring the rook into the game in a single move.
Queenside castling covers more ground — and still happens in one move.
A pawn that just jumped two squares can still be taken as if it had moved one.
A pawn that reaches the last rank is replaced by a piece of your choice.
A queen is obvious. A knight wins the rook.
Step one piece aside and the piece behind it gives check.
Two pieces check the king on the same move. Only flight can save it.
A piece that cannot move without exposing its own king is helpless.
A rook on the eighth rank, and the king has no air.
A knight mates a king buried under its own pieces.