Light every open square
Place lamps in white cells so every white cell is illuminated. A lamp lights its own cell and the open cells along its row and column, stopping at dark blocks. Two lamps may not shine directly at one another.
Akari
Getting your game ready…
How to play
Count beside dark clues
A number on a dark cell requires exactly that many lamps in the cells directly above, below, left and right. Diagonal lamps do not count. Unnumbered blocks still stop light but give no adjacent-lamp requirement.
Mark a place to avoid
Tap a white cell to cycle clear, lamp and cross. A cross is a reminder that you have ruled out a lamp there; it does not block light. Arrows move focus; Enter or Space cycles, 1 places a lamp, 2 a cross and 0 or Delete clears. Undo reverses a change; Hint explains a deduction without placing the lamp for you.
Strategy
Use the dark clues first
A zero rules out its four neighbours. A clue needing every available neighbour forces their lamps. After placing one, follow its whole row and column: those lit cells cannot hold another lamp looking back at it.
Find a cell with one light source
An unlit square may have only one remaining position that can illuminate it. Check both its row and column before filling an attractive empty space. Light can cover several sections at once, but seeing another lamp invalidates the placement.
About the game
Light and interruptions
Six authored boards use lamps, open cells and dark barriers to make illumination visible. Two easier boards use four-by-four cells; four later boards use five-by-five. Cross marks help reasoning; the lamp arrangement determines completion. Solved boards stay visible until Undo or another board choice. Completed boards and your last selection are remembered, but reopening starts that puzzle fresh.