The king can only move more than one square during a castling move. To castle, the king moves two square towards the rook, and rook moves to the other side of the king. This is all one move. You may only castle when :
- All the squares between your king and rook are unoccupied.
- The king has not moved yet
- The rook involved in the castle has not moved yet
- The king is not in check
- The king will not move into check
- The king will not move through a square being attacked
To castle when playing at Chess At Work just move the king. The rook will move automatically if the castle is valid AFTER the move is submitted.