THREE LEVERS
Number-puzzle difficulty isn't one number. It's three different levers a generator can pull, and they feel different in your head.
1. Clue density
Fewer starting digits means fewer anchors, more candidate options per cell, more scanning. A Sudoku with 30 clues is meaningfully harder than one with 35 even if both use the same techniques.
2. Technique depth
Some puzzles solve with naked + hidden singles alone. Others require pointing pairs, x-wings, swordfish, colouring, or chain logic. A puzzle that needs x-wings to crack is in a different league from one that doesn't — regardless of clue count.
3. Search depth
How many cells you have to look at before each placement. Easy puzzles: the next move is one or two cells away from your last. Hard puzzles: the next move depends on a deduction that spans half the grid.
GRIDJOY'S 5 TIERS
Every puzzle type in GridJoy has 5 difficulty tiers. What matters is what changes underneath each label.
Easy (T1) — solvable with one technique, usually naked singles. Designed for learning the rules.
Medium (T2) — naked + hidden singles. The standard "easy" puzzle on every newspaper page.
Hard (T3) — adds pointing pairs and naked pairs. Lower clue density. Most weekend-puzzler difficulty lives here.
Expert (T4) — adds x-wings, swordfish, and some chain logic. Significant time investment per puzzle.
Master (T5) — adds colouring, forcing chains, deep look-ahead. Often 30+ minutes for a strong solver. A few specific puzzle types (Sudoku, Kakuro, Killer Sudoku) can produce genuinely punishing T5s.
WHEN TO STEP UP
Three signals you're ready for the next tier:
- Your times at the current tier have stopped improving for a few weeks. You've absorbed the techniques — now you need new pressure.
- You finish current-tier puzzles without pencil-marking. Either the puzzles are too easy or your visual scanning has caught up.
- You catch yourself getting bored mid-solve. Boredom isn't a moral failing; it's the brain saying "I'm not learning here".
WHEN TO STEP DOWN
Stepping down isn't failure. If a tier consistently frustrates you — multiple puzzles where you stall, guess, or quit — the techniques aren't in your hands yet. Drop a tier, build the muscle, come back.
The fastest path to Master isn't grinding Master puzzles. It's solving lots of Hard ones until the techniques are automatic.
WHY DIFFICULTY VARIES BY PUZZLE TYPE
The same tier label feels different across types because each type has its own technique tree.
A T5 Hitori is a connectivity-and-shading puzzle — totally different brain muscles from a T5 Sudoku. A T5 Hex Maze is spatial path-tracing. A T5 Calcudoku is arithmetic-and-Latin-square. T5 means "hardest in this type", not "hardest overall".
Treat each type's ladder independently. Being a Master-tier Sudoku solver doesn't mean you'll breeze through a Master Kakuro on first try.