Normal Sudoku rules apply Kings are 1s, Rooks are 2s, Bishops are 3s, Knights are 4s. Basically, no King can be "in check". [In detail: No two Kings can be a “Kings Move” apart; No King can be a “Knight’s Move” from any Knight; No King can be on the same diagonal as a Bishop, unless a Knight or a Rook is blocking the path; No King can be in the same row or column as a Rook unless a Knight or a Bishop is blocking the path.] Along thermometer shapes, digits must increase from the bulb end. Clues with arrows outside the grid indicate the sum of the cells along the indicated diagonal. Digits can repeat along these diagonals.