Light Up (BrainBashers)

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Place bulbs until every white square is lit, with no bulb shining on another.

on brainbashers.com

BrainBashers Light Up for 29 October, 10x10 Easy, in play: three bulbs placed round a 3 block light their rows and columns in yellow, beside the check, answer and auto buttons

Light Up on BrainBashers, the puzzle also called Akari, is a grid of white squares and black blocks. You place bulbs that light along rows and columns until every white square is lit, matching the numbers on the black blocks and never letting two bulbs see each other.

About Light Up (BrainBashers)

Light Up, also known as Akari, is a lighting puzzle on a grid of white squares broken up by black blocks. A bulb placed on a white square lights every square in its row and column until the beam hits a black block or the edge. The aim is to light every white square. Some black blocks carry a number, which says exactly how many bulbs sit next to it, up, down, left or right but not diagonally. And no bulb may light another, so two bulbs can never share an open line.

Kevin Stone's BrainBashers posts fifteen of these a day: 5x5, 7x7, 10x10, 15x15 and 20x20 grids, each at Easy, Medium and Hard, with a 25x25 weekly special. The play page ticks off finished squares automatically (you can turn that off), can show dots on lit squares, and has check, answer, auto, print and restart buttons, an option to show mistakes and an optional clock. The help page has a walkthrough.

The set changes at midnight GMT or at the time zone you choose, and the date list keeps a few weeks of earlier days. No adverts, no account.

It suits players who like clean, rule-light logic, and the range of sizes runs from a one-minute 5x5 to a long 20x20.

How to play Light Up (BrainBashers)

Open the Daily Light Up page and choose today's size and level.
Click a white square to place a bulb; it lights its row and column up to the next black block.
Match every numbered black block with exactly that many bulbs beside it, not counting diagonals.
Never let two bulbs light each other, and keep going until every white square is lit.
Check your grid or reveal the answer; new puzzles appear after midnight GMT.

Screenshots

BrainBashers Light Up for 3 October, 20x20 Medium: a white grid scattered with black blocks, some numbered 0 to 3, above the check, answer and auto buttons

Tips

A 0 block means none of its four neighbours holds a bulb; mark them first.
A 4 block, or a 3 against an edge, fills every available neighbour with a bulb.
A white square that can only be lit from one place tells you where a bulb must go.
Use the dots option to see which squares are already lit when the grid gets large.