Tap any tile to select it, then tap any other tile to merge them. Their values add together.
If the result is a prime number, it becomes a prime tile — it stays on the board, scores points, and shows a green ring. Prime tiles are not gone forever: tap one and merge it with anything to build an even bigger prime.
If the result is not prime, 2 new tiles spawn. If you make a prime — from any combination of tiles — 1 new tile spawns. Making primes always relieves board pressure.
Scoring is exponential: prime². Plus a collection bonus equal to the sum of all prime tiles on the board when you score — so keeping primes around pays off.
The board fills up over time. Game over when all 16 tiles are full and fewer than 2 regular tiles remain.
| Prime | Base score | + 3 primes on board |
|---|---|---|
| 7 | 49 pts | +21 collection bonus |
| 13 | 169 pts | +39 collection bonus |
| 23 | 529 pts | +69 collection bonus |
| 47 | 2209 pts | +141 collection bonus |