King on f1: Kingside

King on f1, me on h1 — kingside castling with a catch. The king takes one little step to g1, and I jump straight onto f1 — the square he was just standing on! We swap zones, like soldiers on rotation. The beginner here often thinks the pieces will collide — they won't, castling happens in a single motion. King — onto the rook h1!

Rotation complete: king g1, me on f1. Like clockwork!