Logic Masters Deutschland e.V.

Normal Sudoku rules: Place the digits 1-9 in every row, column and box.

XV: Digits joined by an X sum to 10. Digits joined by a V sum to 5. Not all Xs and Vs are necessarily given.

Palindromes: Digits along a grey line read the same forwards and backwards.

Skyscrapers: Each cell represents a skyscraper whose height is the digit in that cell. Taller skyscrapers obscure the view of smaller ones. Clues outside the grid count how many skyscrapers can be seen in their row or column looking from the clue.