Logic Masters Deutschland e.V.

Rules:

• Classic Sudoku: Every row, column and 3x3 box must contain every number from 1 to 9.
• Sandwich Sum Lines: Every digit along an ochre line (except the ends) must equal the sum of its two neighbours; if the sum is greater than 9, it wraps around (e.g. 10→1, 11→2 etc.).
• Counting Circles: Any digit in a circle indicates exactly how many circles contain that digit.
• Kropki: Two digits separated by a white dot are consecutive; two digits separated by a black dot have a 1:2 ratio.

Play it online in SudokuPad.