Logic Masters Deutschland e.V.

Sample:
Apply classic sudoku rules.
The number on each line is palindrome, that is, reads the same forward and backward.
Numbers outside the grid are Skyscraper clues, which means: Each digit represents a skyscraper of the given height. Higher skyscrapers block the view of lower skyscrapers. Clues outside the grid indicate the number of visible skyscrapers from that direction.