Infinity Sudoku: The World’s Hardest Puzzles

Updated 6 October 2026

Infinity is Suuudokuuu’s tier beyond Hell: a curated set of the hardest sudoku puzzles ever published, the record grids the solving community still argues about, ready to play for free. Every Infinity board is a known puzzle with a published Sudoku Explainer (SE) rating of at least 10.0 — Arto Inkala’s Everest, Platinum Blonde, AI Escargot, Golden Nugget and 96 more — checked for a single solution before it ships. These are the puzzles our hardest sudoku puzzles guide describes; Infinity is where you play them.

What makes a puzzle Infinity

The other tiers are defined by the techniques they require. Infinity is defined by reputation, measured: a puzzle qualifies only if independent raters have published an SE rating of 10.0 or higher for it. Most of the 100 come from a 2011 snapshot of the hardest-puzzle database the sudoku-solving community maintains; the rest are the named classics, taken from the forum threads and publications where they first appeared. Before the set is packed into the app, a Dancing Links exact-cover solver and a bitmask solver both confirm that every grid has exactly one solution.

When you start an Infinity game, the app picks one of those puzzles and disguises it. It relabels the digits, shuffles rows within their bands, columns within their stacks and the bands and stacks themselves, and sometimes mirrors the grid across its diagonal. None of that changes the logic or the rating, so the Everest you play is still Everest, it just does not look like the picture below.

How hard is it, honestly

Harder than anything else in the app, by a wide margin. Our sample of 40 Hell boards measures SE 7.5 to 8.1; Infinity starts at 10.4. The Infinity ratings are not our own measurements. Suuudokuuu’s rater prices the SE ladder only as far as forcing chains and nets and reports 8.5 with a ceiling flag above that, so for these puzzles we quote the figures independent raters publish, as the difficulty rating guide explains.

Our technique engine agrees that these boards sit past its reach. It knows every pattern on the technique index, up to the Nishio Forcing Chain and the Region Forcing Chain, and it still cannot finish a single Infinity puzzle on its own. That does not mean they need guessing; it means they need longer forcing nets than the engine implements. Hints are off by default on Nightmare, Hell and Infinity, and a setting turns them back on if you want the engine’s help for as far as it goes.

Where to go next

Want the record puzzles on paper? Download the printable Infinity sudoku PDF. Not ready for them yet? Step back to Hell Sudoku, where every board needs a forcing chain but stays within reach of our technique ladder. Read the stories behind Everest and AI Escargot on the hardest sudoku puzzles page, compare every tier on the Sudoku difficulty levels hub, or head home.