Magnets

Overview

Magnets arranges domino-shaped slots across a board and asks which slots contain a magnet. A used slot has one positive pole and one negative pole; an unused slot contains neither. Equal poles cannot touch orthogonally, even when they belong to different slots. Clues outside the grid count the positive or negative poles in the corresponding row or column. Some counts may be absent, leaving you to infer them from the surrounding structure. This produces a compact constraint puzzle in which orientation matters as much as occupancy. A slot that seems impossible as plus-minus may work as minus-plus, while another must remain empty. The local engine generates boards and exposes Undo and Restart so tentative deductions can be reconsidered cleanly.

How to Play

Click one end of a slot to place a magnet with its positive pole at that end; click again to remove the magnet. Secondary input cycles the slot through empty, neutral, and an uncertain-magnet mark. Read the symbols next to the row and column totals carefully: a positive count is not a total number of magnets. Place both poles through the slot control rather than treating each half as an independent object. On touch screens, tap near the centre of the intended half and observe the resulting orientation. Finish when all supplied counts and pole-adjacency rules are satisfied.

Tips & Strategy

Begin with a row or column whose zero clue forbids one polarity entirely. Any magnet crossing that line must then have the opposite orientation or be absent. Adjacent parallel slots are useful because placing one magnet may force the polarity of another. Count remaining spaces before filling a nearly complete line: if its missing positive poles equal the available legal positive positions, those positions are forced. Do not count empty slots as negative evidence for both neighbouring lines until you have actually ruled out both orientations. Keep checking that a forced polarity does not create equal adjacent poles across a slot boundary.

About this version

Magnets uses the locally compiled magnets engine from Simon Tatham’s Portable Puzzle Collection. The original authors retain credit under the MIT license. SonoTap provides the browser adaptation and this guide.