Thank you for your feedback! Definitely was hoping to find more music but I suppose that’s just the way the game jams sometimes. The shuffling is done by swapping columns and rows so you can swap columns (all 9) of cells as long as they stay in the same group and swap columns of groups while keeping a valid puzzle. The same can be done with rows. Here’s a great article about the transformations (https://www.shapedoku.com/articles/sudoku-grid-transformations-explained)!
Again thank you for playing!