Shikaku
Divide the grid into rectangles so that each rectangle contains exactly one number equal to its area.
Rules
- The grid must be completely covered by non-overlapping rectangles.
- Each rectangle must contain exactly one numbered clue.
- The number on the clue must equal the area of its rectangle.
The puzzle is solved when all three rules hold simultaneously.
Controls
Keyboard — Navigation Mode
| Key | Action |
|---|---|
Arrows / wasd / hjkl |
Move cursor |
Enter / Space |
Select clue to expand |
Backspace |
Cancel preview or delete rectangle at cursor |
Keyboard — Expansion Mode
After selecting a clue, you enter Expansion Mode. Each side of the rectangle is controlled independently.
| Key | Action |
|---|---|
Arrow / wasd / hjkl |
Expand rectangle in that direction |
Shift+Arrow / WASD / HJKL |
Shrink rectangle from that side |
Enter / Space |
Confirm placement (if valid) |
Backspace |
Cancel, discard preview |
Mouse
| Action | Effect |
|---|---|
| Left click + drag | Draw a rectangle from any cell |
| Release | Place the rectangle if it contains exactly one clue, the area matches, and there are no overlaps |
| Right click | Delete rectangle at cursor |
You can start a drag from any cell, not just a numbered clue. While dragging, the preview turns green when valid or red otherwise. If the rectangle is invalid on release, you stay in Expansion Mode so you can fine-tune with the keyboard.
| Key | Action |
|---|---|
Ctrl+R |
Reset puzzle |
Ctrl+H |
Toggle full help |
Escape |
Return to main menu |
Tips
- Start with 1s and 2s. Small clues have very few possible rectangles, making them easy to place first.
- Use the edges. Clues near corners and borders have fewer valid rectangle configurations, so they constrain the puzzle early.
- Watch for forced placements. If a clue has only one possible rectangle that avoids overlapping placed rectangles, it must go there.