Thirteen Grid
Lightning joins two cards that make 13 across empty cells, and both ends blast the grid open.
How to play
- Every card starts boxed in by grid lines except a small block of free cards with one empty cell among them. A boxed-in card cannot be picked or linked to, and no line runs through it.
- Tap a free card, then another free card that adds up to 13 with it — A is 1, J is 11 and Q is 12. A line of empty cells has to run between them, up, down, left and right; cards side by side need none. Or drag from one to the other. A second tap that makes no link lets go of both.
- Lightning runs along the line and both cards clear. Each end blasts the boxes in a cross round it — directly above, below, left and right, not the corners — and a box that opens frees its card.
- Some boxes have a thick double line. A blast strips it back to a single line, and a second blast opens it. The first level has none; later levels have more, up to half of the boxes.
- A King is 13 by itself: it clears as soon as its box opens, and blasts a cross of boxes open too.
- Open the last box and the cards left link themselves off. Undo takes back a move; New game deals a different board of the same size.
What it trains
- Adding to 13 at a glance, pair after pair
- Choosing which boxes to blast first so the next pair is free
- Spotting a clear path between two cards across a crowded grid
Play Thirteen Grid in your browser: a grid of playing cards boxed in by solid grid lines, with a small block of free cards to start. Pick two free cards that add up to 13 — ace and queen, two and jack, six and seven — side by side or with a clear run of empty cells between them, and a bolt of lightning joins them: both clear, and each blasts open the boxes above, below and beside it. A King is 13 on its own and clears the moment its box opens, and boxes with a thick double line take two blasts. Boards grow from 5×5 to 9×9 with more double boxes as the levels go on, and once no card is boxed in the cards left clear themselves.
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