Normal sudoku rules apply. The digits in two cells joined by a white dot have a fixed difference; those joined by a black dot have a fixed ratio (the ratio is not necessarily an integer, it could be any rational number); those joined by a blue dot have a fixed sum; those joined by a red dot have a fixed product.
https://www.youtube.com/watch?v=IykYoO3JCPQ&ab_channel=CrackingTheCryptic
https://app.crackingthecryptic.com/sudoku/3gJJ7JJpGH
Normal sudoku rules apply. The digits in two cells joined by a white dot have a fixed difference; those joined by a black dot have a fixed ratio (the ratio is not necessarily an integer, it could be any rational number); those joined by a blue dot have a fixed sum; those joined by a red dot have a fixed product.