Candidate Mode
Sudoku with auto candidates
Ruedoku lets you play Sudoku with candidate marks visible, so every empty square can show the numbers still possible for that cell. It is useful for medium, hard, and ultra hard puzzles where manual bookkeeping can hide the actual logic.
Why candidate marks help
A Sudoku candidate is a number that can still fit in a cell without breaking the row, column, or 3x3 box. When a puzzle gets harder, tracking those possibilities is the difference between solving logically and guessing.
Auto candidates keep those possible numbers visible while you work. After you place a digit, the board can remove that digit from related cells. This makes naked singles, hidden singles, locked candidates, and X-Wing patterns easier to spot.
Toggle candidates
Use the Candidates button or press c on the keyboard to show and hide possible numbers.
Use hints
Ask for a hint when the candidate grid is full but no placement is obvious.
Study eliminations
Use the technique guides to connect candidate patterns to real solving moves.
Best uses for auto candidates
- Learning how candidate marks change after each placement.
- Playing harder Sudoku puzzles without writing notes by hand.
- Checking whether a hint follows from a naked single, hidden single, or locked candidate.
- Practicing intermediate techniques such as X-Wing where candidate positions matter.
FAQ
What is auto candidate mode in Sudoku?
Auto candidate mode shows the possible numbers for each empty cell, then updates those candidate marks as the board changes. It helps you focus on logic instead of bookkeeping.
Can I play Ruedoku with candidates enabled?
Yes. Open a puzzle with candidate mode enabled, or toggle Candidates from the toolbar while playing. Keyboard users can press c to show or hide candidates.
Do candidates solve the puzzle for me?
No. Candidate marks organize the possibilities. You still choose placements, ask for hints, or use Auto Play when you want to see the next logical step.