Logic Masters Deutschland e.V.

It seemed only right that aqjhs and I completed a merry-go-round of brutally difficult puzzles after his and my collaborations with MathGuy_12. I came to aqjhs with an idea that I was struggling to bring to life, and to say he ran with it would be the understatement of the year - it was a blast setting with him! Huge thanks to him for contributing his setting wizardry, as well as to Sotehr and my dad for testing.

This is our response to Scojo's Halloween setting prompt, requesting "monstrifiers".

Doppelgänger Sudoku:
• Fill each cell of the main 9x9 grid such that every row, column and 3x3 box contains a 0 and eight different digits from 1-9;
• No two rows, no two columns and no two boxes may be missing the same digit;
• For each 0 in the grid, the digits missing in its row, column and region must be three different digits;
• Fill each outer cell with the digit missing from the corresponding row, column or box.

Phantom Cells:
• A cell is a phantom if the missing digits in its row and column are equal;
• All phantom cells have different digits;
• The value of a phantom cell is increased by the missing digit in its box;
• One phantom cell is shown (ghost emoji).

Values in a cage sum to the given total. Digits may not repeat in a cage (but values may).

On a green Index line, the N-th digit starting from the bulb indicates the position along the line where the digit N appears.