Logic Masters Deutschland e.V.

Rules:

- 4x4 Sudoku: Place the digits 1-4 once in every row, column and 2x2 box.

- Fog: The grid is partially covered in fog. Filling in correct digits will clear the fog from that cell and perhaps from some other cells as well.

- Little killer: The digits on the negative diagonal must sum to 9.

- Killer cage: The middle 2x2 square (i.e. the square having a cell from every box) must contain all digits.

- Unique lines: Furthermore, the grid contains the following four lines:

-- German whisper (green): Adjacent digits must differ by at least 2.

-- Parity line (red): Adjacent digits must have different parity (even/odd).

-- Region sum line (blue): Box borders divide the line into segments with equal sums.

-- Thermometer (grey): Digits must strictly increase from the bulb end.

All lines are represented once and must have the same length. Lines don't branch and only move orthogonally. Each cell is visited once by exactly one line. A digit cannot occur twice on the same line.

Link to Sudokupad