Akari Masyu is a hybrid of Akari and Masyu, in which the cells in a grid are lit-up by placing lightbulbs and no lightbulbs shine on each other and a single, non-intersecting loop that passes through all empty cells is drawn.
The objective is to light up all white cells, and draw a single, non-intersecting loop, subject to the following rules:
- Lightbulbs shine every cell vertically and horizontally until they reach a black cell or the boundary.
- Numbers in some black cells denote the number of lightbulbs in adjacent cells.
- Lightbulbs themselves are not lit by other lightbulbs.
- All cells not occupied by lightbulbs must contain a single, non-intersecting loop.
- At black cells the loop has a turn of 90°. The loop must also go straight through the cells immediately before and after on the path.
- At white cells the line travels straight through. The must turn in the cells immediately before and/or after on the path.
A standard 10x10 akari masyu puzzle and its solution.