Tap tiles one after another to build a path. Each tile you add must touch the previous one directly, above, below, left or right. Diagonals do not count. Tap a selected tile again to remove it.

Press Submit match when you think the chain adds up to the target. You need at least two tiles. If the sum is wrong, the game tells you the sum you made and the target, and the selection is cleared.

A correct match removes those tiles, drops the remaining tiles down their columns, and fills the gaps at the top with new random numbers. A new target is then chosen.

Each run has one countdown for the whole game: Easy is 75 seconds, Medium is 45 seconds and Hard is 40 seconds. When it hits zero the run ends.

A match scores ten points for every unit of the target plus fifteen points for every tile in your chain. A target of 12 solved with four tiles scores 12 × 10 + 4 × 15 = 180. The same target with only two tiles scores 150.

Because every tile adds fifteen points, longer chains are worth more, but a long chain takes longer to find, and the clock is shared by the whole run.

Scan for pairs first. Two tiles that already add to the target are the fastest points, and the new tiles that fall in may make the next target easier.

Remember that small numbers are flexible. A board with several 1s, 2s and 3s can build almost any target, while a board of large numbers needs a precise combination.

• Easy uses the numbers 1 to 9, with targets up to 15 and 75 seconds in total.
• Medium uses the numbers 1 to 15, with targets up to 30 and 45 seconds in total.
• Hard mixes in negative numbers from −5 to 15, has targets up to 25, and gives you 40 seconds. On Hard the target also changes every 12 seconds and clears your current selection, so you have to be ready to restart a chain.

On Hard, a negative tile can be a tool rather than a problem. If your target is 10 and you have an 8 and a 7, adding a −5 gets you to 10 with three tiles. The extra tile also adds fifteen points. Look for these small correction tiles next to larger numbers.

Imagine the target is 12 and the top row reads 5, 3, 4, 7. The chain 5, 3, 4 adds to 12 and uses three neighbouring tiles, so it scores 12 × 10 + 3 × 15 = 165 points. If the 4 also sits above a 8, you could instead take 4 and 8 for the same target with two tiles, which scores 150 and clears a different part of the board. The longer chain scores more, but the shorter one may leave a better layout for the next target.

That trade-off is the whole game: a few extra points now against how quickly you can find the next match. On Easy it is worth taking the longer chain when you can see it immediately. On Hard, with the target shifting every 12 seconds, the quick match is usually better.

Clearing tiles changes the board in two ways: the cleared cells are refilled with random numbers, and the tiles above them drop. Matches near the bottom of a column shift the most tiles, so they reshuffle more of the board. Matches near the top disturb less, which is useful if you have spotted another match you want to keep.