Logic Masters Deutschland e.V.

This puzzle was directly inspired by The Book Wyrm's Full Full Rank Rank and Sotehr's Step Sums. After having solved FFRR, I wanted to make my own nested puzzle, but no constraints inspired me with ideas until I test-solved Step Sums. This was the result.

The rules are as follows:

• Inner 9x9 Sudoku: Place the digits 1-9 once in every row, column, and 3x3 box. Digits separated by a kropki must have a difference of 1 and digits on gray squares must be even.
• Inner Periodic Sums: All 36 cells bordering the Sudoku grid have a number equal to the sum of N and every Nth digit in the row/column moving away from the clue, where N is the first digit seen from the clue. Only digits within the Sudoku grid are taken into account.
• Outer Periodic Sums: Clues outside the inner periodic sums indicate the sum of N and every Nth digit in the row/column moving away from the clue and including the inner periodic sums, where N is the first digit seen from the clue. Double-digit inner clues are read as two single-digit numbers. Read the tens digit first when reading left to right/top to bottom and the ones digit first when reading right to left/bottom to top.

The puzzle is available on SudokuPad and Penpa (answer check only on digits within the Sudoku grid). Watch your step at the end!