Sort a grid of grey dominoes into magnets and blanks so every row and column hits its plus and minus counts.
Magnet Dominoes starts you off with a grid that is already cut into dominoes, every one of them plain grey. Some hide a magnet, positive on one side and negative on the other. Others are blank. Your task is to figure out which is which, and for every magnet, which end points where.
Numbers around the edge of the board are your only clues. With a bit of patience they always lead to one answer, so there is no need to guess.
The rules
Each domino spans two squares. A magnet places a plus pole in one of them and a minus pole in the other. A blank domino leaves both squares neutral.
The counts along the top and left, marked with a plus sign, tell you how many plus poles sit in that line. The counts along the bottom and right, marked with a minus sign, do the same for minus poles. If a number is missing, that count is simply not given.
Like poles repel. Two plus squares can never touch along a side, and neither can two minus squares. Neutral squares are free to sit next to anything, including each other.
Placing pieces
Click a domino once to drop in a magnet whose plus pole lands on the half you picked. A second click reverses it, and a third empties the domino again. Right-click instead to mark the domino blank. A second right-click swaps the blank for question marks, a private note meaning “this is a magnet, direction unknown.” A third clears it.
Strategy notes
Start with simple sums. When a row’s plus and minus counts add up to the row’s length, it has no blank squares at all. A plus count of 0 means every square in that line is either minus or neutral.
Magnets that lie flat inside a row give that row one plus and one minus. If the row’s two counts differ, the difference must come from standing magnets that only poke one end into it.
Each placed magnet also restricts its neighbors. The squares touching its plus end cannot be plus, and the squares touching its minus end cannot be minus. Follow that chain outward and whole areas of the board often fall into place. Grey out each clue as you meet it so you can focus on the rows still open.
Sizes and difficulty
The preset list holds eight boards across three sizes, 6x5, 8x7 and 10x9, each at Easy or Tricky. Custom sizes are available too, and an option to strip some clues makes the puzzle harder still. A Solve button is there if you want to check the answer.
Controls
| Action | Keyboard | Mouse | Touch |
|---|---|---|---|
| Place a magnet, flip it, then remove it | Arrow keys to move, then Enter (repeat to cycle) | Left-click a domino (repeat to cycle) | Tap a domino with Tap set to Magnet |
| Mark a blank domino, then "cannot be blank", then clear | Space (repeat to cycle) | Right-click a domino (repeat to cycle) | Press and hold, or set Tap to Blank domino and tap |
| Grey out a finished clue | — | Click the clue | Tap the clue |
| New game, undo, redo | N, U, R | Menu buttons above the grid | Menu buttons above the grid |
Magnet Dominoes FAQ
Does Magnet Dominoes work on a phone or Chromebook?
Yes. On a touchscreen, tapping a domino adds a magnet or turns it around, while a long press sets it as blank. A switch below the grid lets you swap those so a tap marks blanks instead. On a Chromebook, click and right-click work, or use the arrow keys with Enter and Space.
Will I ever have to guess?
No. Every puzzle can be worked out with logic alone. If you feel stuck, there is always a deduction left to find, usually from a row or column count or from a pair of poles that would end up side by side.
Is it a solo puzzle?
Yes. It is a one-player logic game with no timer. You can start a new board with N whenever you like, and undo or redo with U and R as many times as you need.
How do I know the puzzle is solved?
The grid flashes once every domino is set correctly, with each magnet facing the right way and each blank marked. You can also click a clue to grey it out once its count is met, which helps you see what is left.
