Rectangles / Shikaku
Which rectangle shapes fit a Shikaku clue?
A clue gives the rectangle’s area, not its width or perimeter. List whole-number factor pairs, then reject shapes crossing the board edge or enclosing another clue. Every rectangle must contain exactly one clue.
Worked example
A clue 6 permits 1 × 6, 2 × 3 and their rotations. An L-shaped group of six cells is not a rectangle.
What to check on your board
Apply the rule above to your current board, then verify the remaining puzzle constraints. The example explains a local deduction; it is not a solution to every randomly generated board.
Checking your next move
For each factor pair, try both orientations and check the proposed corners against the board. Reject any rectangle containing another clue before spending time fitting its neighbours. After choosing a shape, count its cells as width × height rather than tracing its perimeter.
Using this reference
For Rectangles / Shikaku, read the rule and the worked example together before opening the game. Separate what the rule explicitly requires from what only seems likely on the current board. A useful next move is one you can explain from the visible constraints, not merely a pattern that looks familiar.
If you get stuck, isolate a smaller part of the position and list what is still possible there. After a move, check the affected rows, regions or connections again. The reference explains the documented rules; progress, controls and save behavior belong to the linked game.
Read the developer’s manual ↗ · Open the developer’s browser version ↗
Manual inspected: · Simon Tatham & contributors · MIT