Logic Masters Deutschland e.V.

This is my first puzzle. I made it as a birthday present for my sister. I always liked 159-Indexer so I made a Puzzle which uses columns and rows (besides some other clues). I think it became quite good.

• Normal Sudoku rules apply.
• Partial 159-Indexer: Digits in red cells in columns 1, 5, and 9 indicate the column in which the digit 1, 5 or 9 (respectively) appears in that row. Digits in blue cells in rows 1, 5 and 9 indicate the row in which the digit 1, 5 or 9 (respectively) appears in that column.
• Scyscrapersums: Clues outside the grid indicate the sum of the visible digits in the direction of the arrow, where digits block the view for all lower digits behind them.
• Uncertain clues: Exactly one of the Skyscraper-clues is incorrect. Additionally the first digit in the direction is equal to the corresponding row or column number (for the wrong clue).
• Quadruple clues: A digit inside a white circle appears in at least one of the four cells surrounding that circle.