Logic Masters Deutschland e.V.

All feedback and comments will be much appreciated! This puzzle can be tackled in many different ways, if you enjoy it feel free to tell me how you got to your breakthrough!

Hypercube

Link to the puzzle

Rules:

Do normal sudoku rules apply? Find out for yourself!
All cells in the grid must contain a digit from 1 to 9.

Little Killer: A clue outside the grid gives the sum of the digits along the indicated diagonal.

HyperSudoku: Two different cells must contain different digits if they have two or more of the following properties in common:

• Their row numbers belong to the same entropy set (see below);
  
• Their column numbers belong to the same entropy set;
  
• Their row numbers belong to the same modulo set (see below);
  
• Their column numbers belong to the same modulo set.
  

The modulo sets are {1, 4, 7}, {2, 5, 8}, {3, 6, 9}, while the entropy sets are {1, 2, 3}, {4, 5, 6}, {7, 8, 9}.