Light Up (Akari)

New to Akari? The Last Lighthouse lets you explore six connected rooms in an interactive world.

Tap a white square to place a bulb; tap again to remove it. A bulb lights its row and column until a wall. Light every white square without letting bulbs shine on each other. Small corner rays also identify lit empty squares and notes.

A number on a wall is the exact number of bulbs beside it, up, down, left and right. Diagonal bulbs do not count. Unnumbered walls block light but do not set a bulb count.

Choose Mark to add or remove a no-bulb note. Switch back to Bulb to place lights. Marks are notes, not illuminated squares; another bulb must still light them.

Keyboard: Tab to the board, arrow keys to move between white squares, Enter or Space to act. M changes Bulb/Mark mode, X toggles a mark on the focused square, H asks for a hint, Ctrl/Cmd+Z undoes, Ctrl/Cmd+Shift+Z or Ctrl/Cmd+Y redoes.

Your current puzzle and solved/seen boards save in this browser when storage is available. Undo/redo history lasts for this session. There is no device sync; the original puzzle bank is finite.

A 0 wall excludes bulbs in all its neighbouring white squares. When a numbered wall already has every bulb it needs, its other neighbours cannot contain bulbs. Look for an unlit square with just one possible light source.

Hint checks your current bulbs and marks, then explains a supported deduction. Apply hint makes that move. If your choices conflict, undo or change a bulb or mark.

Reveal shows the complete answer and marks the puzzle as assisted. It is separate from a hint.