Logic Masters Deutschland e.V.

Paint by No Numbers

(Published on 30. October 2026, 22:09 by berdy)

I wanted to try setting a color-based Sudoku that wasn't just a numbers Sudoku with a slightly inconvenient interface. My ambition was to make a puzzle that felt more intuitive to reason through with a color palette than with modular arithmetic. I hope I have achieved that in this puzzle; if not, feel free to solve the numbers based version!

I found this puzzle to have a good mobile solving experience!
Rules
Color sudoku
Shade every cell. Each row, column and 3×3 box contains red, orange, yellow, green, blue and purple once each, plus three gray cells. The given purple cell keeps its color.
Color wheel
The color wheel runs red → orange → yellow → green → blue → purple → red (gray is not on the color wheel). There is no start or end color-- it is a wheel.
Slow gradient lines (cadmium yellow): each successive cell repeats the previous cell's color or advances one position around the wheel. Choose one gradient direction for the whole line.
Constant-step lines (ultramarine blue): each successive cell advances the same number of positions around the wheel in one direction. Direction and step size may vary between different lines.
Mixing arrows: combine all the primary ingredients present on a shaft to obtain its circle’s color. Red, yellow and blue are the primaries:
  • Orange = red + yellow
  • Green = yellow + blue
  • Purple = blue + red
  • Gray = all three
Repeated ingredients add nothing: red + red = red, red + orange = orange, and orange + blue = gray. Gray is allowed anywhere on arrows; any mixture containing gray is gray.
Warm/cool cells: an orange inset glow means red, orange or yellow; a blue-gray inset glow means green, blue or purple.
More puzzles by berdy →?Feeling lucky?

Solution code: The colors in row 1, from left to right (9 letters). Use R=red, O=orange, Y=yellow, G=green, B=blue, P=purple and X=gray.

Solved by zeniko, palletpusher
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Comments

on 2. November 2026, 03:30 by palletpusher
Delightful! I loved the aesthetic of the brushstroke lines, the novel arrow logic, and particularly appreciated the inclusion of the colour wheel mnemonic outside the grid.

I did also find this puzzle quite difficult. Partly skill issue, partly because there's no separate "corner colour mark" in the software. I unstuck myself by breaking the rules and adding numbers to my solve, but all the logic was indeed done on the colour wheel rather than modular arithmetic, so you did indeed achieve the intuition goal.

Had a lovely solving experience on mobile! I overwrote the default purple with a shade more contrastive to orange and was only briefly perplexed by the inclusion of the unused "cool cell" rule (I couldn't really tell which clue r6c6 was supposed to be, and clarified by checking against the numbers-only version).

Very enjoyable. Thanks so much for sharing this, berdy!

on 1. November 2026, 20:58 by berdy
@zeniko Thanks for playing! I'm impressed by your artistic eye, those are great calls haha

on 31. October 2026, 23:11 by zeniko
Dieses Rätsel hat sich mit den Farben gut lösen lassen. Der Farbkreis in der Ecke war dennoch hilfreich. Das Bild liegt wohl zwischen einer Kandinsky-Impression und einem Mondrian, eventuell mit einem Hauch Klee. Danke fürs Teilen.

Difficulty:3
Rating:N/A
Solved:2 times
Observed:0 times
ID:000VSL
Puzzle variant Online solving tool
Sudoku

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Solution code:

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