Logic Masters Deutschland e.V.

Standard Sudoku rules apply.
Killer rules apply. Digits can not repeat in a box.
Disjoint groups are in effect. All digits appear in different places in all 3X3 boxes. Basically, similar positions in 3X3 boxes all act as extra regions.
Little Killer rules apply. The sum of a diagonal being pointed at is shown outside the grid.
Sandwich Sudoku rules apply. The formula outside the grid is the sum of the sandwich between 1 and 9 for input X.
The highlighted area contains each of the digits 1-9 exactly 4 times.

Butterfly rules are in effect.

In chaos theory, the butterfly effect is the sensitive dependence on initial conditions in which a small change in one state of a deterministic nonlinear system can result in large differences in a larger state.
This puzzle has two solutions. There are 2 values that can be chosen for X, the choice drastically affects the solving path and the finished solution. You need both solutions for the solution code.

Kropki Rules apply. All possible dots that have overlap between the 2 possible solutions are given. If there is a kropki pair in 1 puzzle (like 2-3 or 4-8) but no dot between them, then the other puzzle can't have a pair in the same cells. This works as a negative constraint that can be put to your advantage when solving the second puzzle, or if you were to do them simultaneously. Just to be clear, both solutions can be found without this knowledge.

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