Suguru

Einstein is the highest difficulty we offer. Each puzzle is a 14×14 grid with only about 10% of cells given, and every puzzle carries a guarantee: solvable through pure logic, no trial and error needed. Our constraint propagation engine certifies each puzzle before it ships.

You need every technique at once. Naked singles, hidden singles, cage completion, cross-cage deduction, and multi-step chain reasoning. The solving path rarely follows a single strategy — you switch between techniques as the grid opens up.

A clean solve in under 15 minutes is fast. An hour is normal. For technique refreshers, the strategy guide covers everything you need.