About
Puzzles you can trust.
Most sudoku you find is generated quickly and never checked twice — which is how you end up with a "Hard" puzzle that's secretly ambiguous, or an "Easy" one that's actually a slog. This app takes the opposite approach: nothing reaches your screen until it's been proven, not just produced.
Every puzzle is proven, not just generated
Behind every board is a completed grid, filled in by backtracking through valid digits until all 81 cells are set. From there, cells are removed one at a time, in random order — but only if the solver can still find exactly one way to finish the board without them. The moment removing a cell would open the door to a second solution, that cell stays. What's left is a puzzle that's hard because of what it asks of you, never because it's unfair.
Difficulty is a rubric, not a guess
Easy, Medium and Hard aren't picked by hand — they fall out of exactly one number: how many clues the finished puzzle starts with. Fewer clues means less to work from, which is what actually makes a board harder to solve. The same rule labels every puzzle in the app, whether it was generated for you or built by another player, so a tier always means the same thing.
Once played, always the same puzzle
A puzzle can't be edited after it's created — not by you, not by an admin. The exact board you started stays that exact board for as long as it exists, and so does the complete history of every attempt at it. Puzzles don't shift under you, and neither does the record of how you (or anyone else) solved one.
Built move by move
Your play isn't reduced to just a finished board. Every move you make — every digit placed, every cell cleared — is appended to a log in the order you made it and never rewritten. That's what lets you come back to an in-progress puzzle exactly as you left it, and look back afterward over the exact path you took to solve it.