Logic Masters Deutschland e.V.

This was set for Scojo's Setting Saturday prompts. ChinStrap redeemed this prompt to create a puzzle inspired by this year's Imposter Event, run by Scojo.

Many amazing puzzles came out of this event, but my main source of inspiration was this puzzle by Oddlyeven. It is an amazing puzzle that I highly recommend you check out!

Thanks to lmdemasi for testing!

Here is a an example puzzle that is logically solvable:

Rules:

• Doppelgänger Sudoku:
  • Place nine Doppelgänger cells so there's exactly one in each row, column and box.
  • Each Doppelgänger cell contains the digit 0. The remaining eight cells in the row, column, or box contain eight out of the nine digits from 1 to 9 (i.e. it's missing one digit that is not 0)
  • 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, its column, and its box must be three different digits.
  • In the outer regions, place the missing digits from the corresponding row, column, or box within the 9x9.

• Values along green German Whispers lines must have a difference of at least 5.

• Values in grey minimum cells must be strictly smaller than all orthogonal neighbors.

• Clues outside the 9x9 grid accompanied by arrows provide the sum of the indicated diagonal. Digits and values may repeat along a diagonal if allowed by other rules.

• Clues outside the 9x9 grid in squares are numbered rooms clues. The value in the cell closest to the clue indexes the nearest instance of the clue in the row or column. If the clued value does not appear in the row or column, the index will have a value of 0.

• Parallel Universes:
  • Within this puzzle, four different universes exist simultaneously.
  • In each universe, exactly one of the four instances of each clue type listed above is correct, and no clue can be correct in more than one universe.
  • For a given Doppelgänger cell, its value is different across all universes.
  • The value of the Doppelgänger cells in each universe are as follows:
    1. All Doppelgänger cells have a value of 0.
    2. All Doppelgänger cells have a value of the missing digit from its row.
    3. All Doppelgänger cells have a value of the missing digit from its column.
    4. All Doppelgänger cells have a value of the missing digit from its box.