Sudoku and Shingoki are both grid-based logic puzzles you solve by pure deduction, so solvers naturally wonder how alike they really are. The short answer: Shingoki is distant to Sudoku. Below we lay out what the two share, where they part ways, and whether the skills you have built on Sudoku will carry over.
- Grid: Dot grid with numbered circles
- Closeness to Sudoku: Distant
- Also called: Traffic Lights
What is Shingoki?
Draw one closed loop through every circle; white circles are passed straight, black ones force a turn, and each number is the total length of the two straight runs from that circle. Here are the rules in full:
- Draw a single closed loop along the grid, through every circle, with no crossings or branches.
- At a white circle the loop passes straight through; at a black circle it makes a 90° turn.
- A circle's number is the combined length of the two straight segments leaving it.
What a Shingoki looks like
In Shingoki you draw one closed loop through every circle. A white circle must be passed straight through; a black circle forces a 90° turn; and the number inside a circle is the total length of the two straight runs leaving it. Here is a small solved loop.
The black corner circle (a turn) sums its two side-runs to 4; the white circle (straight through) sums its left and right runs to 2.
Both are pure-logic, single-solution puzzles that reward marking impossibilities — but Shingoki draws a loop on the lines rather than filling cells, so it shares Sudoku's mindset, not its machinery. A close cousin of Slitherlink and Masyu.
What Shingoki shares with Sudoku
- Both are single-solution logic puzzles solved by pure deduction.
- Both lean on marking what is impossible — here, edges the loop cannot take.
How Shingoki differs from Sudoku
- You draw a loop on the lines, not digits in cells.
- The clues govern segment lengths and turns, not row, column or box sets.
Do Sudoku skills transfer?
No digit technique applies directly, but chaining forced edges out from each clue is the same "prove it before you commit" discipline Sudoku builds.
The verdict
Shingoki is a cousin of Slitherlink and Masyu: a loop puzzle sharing Sudoku's logical purity but none of its digit machinery.