Tercet Puzzle

Tercet is a numbers game played on a grid. One digit is the sum of the others: the cells go.

THE RULE
Link neighbouring cells — in a line, along a diagonal, or bending at an angle. The path crosses freely over cells that are already empty. If the digit at one end equals the sum of all the others, they disappear. Empty the whole grid to win.

TWO WAYS TO PLAY
Snake: the chain is any length, three cells or ten. The longer it runs, the more it scores.
Trio: exactly three cells. Shorter, sharper, quicker.

THE LIFEBUOY
Every grid can be emptied — but the order of the moves can lose the way out. When no move is left, a lifebuoy winds the game back to the last playable moment and hands the grid back untouched, one breath before the mistake. One to start with, one more for every grid cleared without spending any.

WHEN IT ENDS
No lifebuoy left, and the game stops. It then shows the way out that existed, move by move.

THREE SIZES
9x6 to learn, 9x9 to settle in, 9x12 for no mercy.

IT ALL STAYS ON THE PHONE
No account. No sign-up. No ads. No trackers. No network permission at all: the game cannot send anything anywhere, and it works on a plane, in a tunnel, or far from any signal.

Ten languages: English, French, German, Spanish, Italian, Portuguese, Greek, Arabic, Japanese, Korean.