Expert is the notes threshold. Below roughly 55 clues, holding candidates in your head stops working — the players who cross this line are the ones who externalize their thinking into notes and let eliminations do the work.
What changes at 52 clues
Two thirds of the grid must be deduced. Direct scans still produce moves, but the decisive placements now come from eliminations: proving a cell can only hold one candidate because every alternative is blocked somewhere.
Notes in two dimensions
Color sudoku notes are richer than classic sudoku notes: a cell has candidate digits AND candidate colors. Mark both. The magic is the interaction — eliminating a color from a cell can kill a digit candidate elsewhere, because the corresponding digit-color pair is already used somewhere else on the board.
Cascade thinking
Every placement triggers three waves: its row/column/region lose a digit and a color; its digit-color pair dies everywhere; and notes shrink globally. After each move, spend two seconds asking « what did this just unlock? » — on Expert, chains of 3-4 forced moves are the normal rhythm.
Keep the scans running
The Rainbow and Chromatic Circle scans from Hard remain your openers — run them to seed the notes, then switch to elimination mode. Alternating scan → notes → cascade is the Expert loop.
When to move up
Hint-free Expert wins mean you are ready for Master (43 clues), where deduction chains stretch across half the board. Your Expert rating is safe: every level is ranked separately.
Frequently asked questions
Are notes required on Expert color sudoku?
Practically yes. Below ~55 clues there are too many open candidates to track mentally; noting candidate digits and colors per cell is what makes Expert solvable comfortably.
What is cascade elimination?
Each placement removes its digit and color from the row, column and region, and kills its digit-color pair across the whole grid — one move often unlocks a chain of forced placements.
How is Expert generated?
Expert grids are pre-computed server-side from a bank verified by a CP-SAT solver: 52 clues, unique solution proven offline.
Level guides: ← Hard (62 clues) · All 6 levels · Master (43 clues) →
Ready to try? Play Suirodoku free — same grids and progression on web, iOS and Android.