What is the magnets puzzle?
The magnets puzzle is a logic grid divided into dominoes. Every domino is either a magnet, with a plus end and a minus end, or a blank piece with no poles. Numbers around the edge tell you how many plus and minus poles each row and column holds, and the one physical rule is that like poles repel, so two pluses or two minuses can never sit side by side.
Play the magnets puzzle online free here, with Easy and Tricky boards from 6×5 up to 10×9.
Where the puzzle comes from
Magnets is a newer member of the family of grid puzzles. The rules used here follow the version listed in the puzzle archive at janko.at, where it appears under its German name, Magnete. The domino outlines are given from the start, so your job is to decide what each domino holds, not where it lies.
How to play here
Pick a size and level on the start card, then press Play. Click or tap a square to place a magnet with its + end on that square and its − end on the other half. Tap again to flip it, and a third time to clear it. To mark a domino as blank, right-click it with a mouse, or turn on Mark in the dock and tap it on a phone. A second mark adds question marks, meaning “this can’t be blank”, and a third clears it. Tap a number at the edge to grey it out once that row or column is done.
Undo, Redo and New puzzle are in the dock. The pause menu has Restart and Solve.
A step-by-step way to solve
- Clear the zero lines. A row or column with 0 for a sign can’t contain that sign. If both are 0, every square in it is blank.
- Check the full lines. If a row’s + and − counts add up to its number of squares, there are no blank ends in it at all.
- Use the magnet halves. A magnet lying along a row puts one + and one − in that row. A magnet crossing the row puts only one pole in it.
- Spread with the repel rule. Every pole you place stops the same sign from appearing on the four squares beside it.
- Count blanks last. When a row has all the poles it needs, every other domino end in it must be neutral.
Why play magnets?
Magnets mixes counting with a simple physical idea that everyone knows from fridge magnets, and that makes the rules easy to remember. The Tricky level adds hidden clues for experienced solvers. If you like it, try Binairo, which uses a similar alternating logic, or Dominosa, where you have to find the dominoes yourself.
How to play Magnets
- The grid is split into dominoes. Each one is either a magnet, with a + end and a − end, or a blank with two neutral ends.
- The numbers outside the grid say how many + poles and how many − poles are in each row and column.
- Two identical poles may never touch side by side or above and below. Touching at a corner is fine.
- Neutral ends can sit next to anything.
- If the grid has an odd number of squares, one square is simply left blank.
Magnets tips
Start with the zeros
A row with 0 under + has no plus poles at all, so every magnet crossing it must put its minus end there. When both counts are 0, every square in that row is neutral.
Use the alternating pattern
Because like poles can't touch, any unbroken run of poles alternates + − + −. Once one pole is fixed, its neighbors in the run follow.
Mark dominoes that can't be blank
When the counts prove a domino must hold a magnet but you don't know which way round, mark it with question marks. It saves you working it out twice.
Frequently asked questions
How do you solve a magnets puzzle?
Start with rows and columns whose counts are 0 or very high, place the poles that are forced, and then use the no-touching rule to spread out from there. Each placed pole fixes its partner at the other end of the domino.
Can two minus poles touch diagonally?
Yes. Only poles that share a side repel. Diagonal neighbors can be the same sign.
What is the difference between Easy and Tricky?
Tricky boards need more reasoning about blank dominoes and row and column counts. Some Tricky boards also hide a few of the edge numbers.
