Logic Masters Deutschland e.V.

"断幺九(duàn yāo jiǔ)" is a yaku in mahjong, literally meaning "without 1 and 9", requiring the entire hand contains 2 to 8 only.

Rules:

Normal Sudoku Rules partly apply. Place 2 to 8 in the grid so that every row, column and box consists of 7 digits (2 to 8 once each) and 2 blanks.

Kropki Dots: 2 digits seperated by a kropki dot must be consecutive (for white dots) or in 1:2 ratio (for black dots). 2 digits in a single row/column will be considered as "seperated by a kropki dot" if what is between the 2 digits in the corresponding row/column is a full-blank region along with the kropki dot (like: A.B/A.0B/A.00B/A0.0B, 0=blank)

Regions between 2 kropki dots or one kropki dot and the grid's border in a single row or column cannot be full-blank. (like: r5c5/r7c9)

Green Line/Dutch Whisper: Adjacent 2 digits along the green line must differ by ≥4. Digits will be considered as "adjacent" if seperated by a full-blank region along the line. (like: A0B/A00B)

Light-blue Line/Region Sum Line: Digits along region sum lines have the same sum within each box the line passes through. Blanks are regarded as 0 on the light-blue line.

Purple Line/Ranban: Digits along the purple line must form a non-repeating and consecutive sequence in any order. Blanks are not counted to the sequence but may or may not exist on the line. (like: 230/657/504)

Each line must contain at least 2 digits.

Let's Go! (CTC)