Eratostene

Eratostene is a math puzzle game where you hunt down hidden prime numbers in a 5×5 grid and add them up before time runs out. Simple rules, growing difficulty — spotting primes gets trickier and the sums get tougher as you climb through the levels.

This is a free 25-level demo. The full game features 200+ levels across multiple game modes, a leaderboard, and ongoing races. Enjoy the taste, then check out the full experience!

Play the full game → Mathemory

Note: If you see the "please rotate your device" message even on PC, try zooming the game.