Logic Masters Deutschland e.V.

Rules:

Quattroquadri: Fill the grid with the digits 1-9 so that no digit repeats within a row, column, or 3x3 box.

Klein Bottle: Row numbers that sum to 7 are connected along the left and right sides of the grid (e.g. R1C1 and R6C6 are considered orthogonally adjacent, as are R2C1 and R5C6, R3C1 and R4C6, etc.). Column numbers that sum to 7 are connected along the top and bottom sides of the grid (e.g. R1C1 and R6C6 are considered orthogonally adjacent, as are R1C2 and R6C5, R1C3 and R6C4, etc.).

X-Sums: Numbers outside the grid show the sum of the first x digits from that direction, where x is the first of those digits. If the value of x exceeds 6, the sum wraps around the grid and continues. For example, if R5C6 were 8, the sum would go left across all of Row 5 and then pick up the last two cells of Row 2.

Solve online:

SudokuPad