1. Start with the biggest clues
This is the overlap technique. Picture the block pushed as far left as possible, then as far right as possible: any cells covered in both cases must be filled.
In a row of 10 cells, a block of 7 sits at most as far left as cells 1 to 7, and at most as far right as cells 4 to 10. So cells 4 to 7 are certain. The quick rule: a block of length k in a line of n cells gives 2k − n certain cells in the middle, as soon as k is more than half of n.
2. Work out the slack in each line
Add up the blocks plus one empty cell between each block. For "3 2 4" over 11 cells: 3 + 1 + 2 + 1 + 4 = 11. The total equals the length: the line has only one solution, so fill it straight away.
If the total is shorter, the difference is the slack. Every block longer than the slack gives certain cells. For "4 3" over 10 cells: 4 + 1 + 3 = 8, a slack of 2. The block of 4 must cover cells 3 and 4, and the block of 3 must cover cell 8.
3. Use the edges
A filled cell against the edge pins down the first block. If the first cell of a row is filled and its first clue is "3", cells 1 to 3 are filled and cell 4 is empty.
The same reasoning works against a cross: a cell known to be empty acts like an edge. A block of 4 that only fits between a cross and the edge of the grid almost places itself.
4. Cross out everything that is finished
As soon as a row or column has all its blocks, put crosses on its remaining cells. Lines marked "0" can be crossed out entirely from the start.
Crosses do not count towards the win, but they change how you read the grid: a column with half its cells crossed out solves like a shorter line, with less slack and so more certain cells.
5. Don't rely on lit-up clues alone
A clue lights up as soon as the block lengths in its line match. It does not guarantee those blocks are in the right place. Before crossing out a lit line, check that every filled cell is confirmed by its column.
Another useful signal: if the board shakes, you have placed as many filled cells as the picture needs, or more, without solving it. At least one cell is wrong, so there is no point adding more. Go back to the row and column intersections to find it.
6. Only place a cross when you are sure
Any move that contradicts the picture counts as a mistake: a cell filled that should stay empty, but also a cross placed on a cell that should be filled. Correcting it later, or undoing it, does not erase the mistake already counted.
Be especially careful when dragging to paint: every cell painted by mistake counts. In an uncertain area, go one cell at a time.
7. Keep the joker for real dead ends
The joker reveals a cell you have not marked yet, filled or empty, and locks it. It is unlimited, but each one costs 60 points out of 1,000.
A mistake, on the other hand, costs little on a large grid: half the performance is spread across all the cells, so about 0.5% per mistake on a 10×10 grid. A joker is therefore worth a good ten mistakes on such a grid. Save it for when no row or column gives you anything more.
Does time count?
Yes. The reference time is 5 minutes: beat it and you earn a bonus of up to 20%; go slower and a gradual penalty kicks in, capped at 25%. The techniques above help here too: they stop you fumbling around.
Going further
For a grid solved step by step, see our beginner's guide to Pixelo. If you enjoy this kind of deduction, our pick of games like picross and our Binero tips will keep you going.