Normal sudoku rules apply. The digits along each arrow must sum to the number in its circle. There are six different colors of lines in this puzzle. Each color corresponds to a different one of these constraints: - Dutch Whispers (adjacent numbers on the line must differ by at least 4); - Entropic (any three adjacent digits on the line must be one each of 1-3, 4-6, and 7-9); - German Whispers (adjacent numbers on the line must differ by at least 5); - Palindrome (the numbers on the line form the same sequence no matter which end you start from); - Region Sums (if the line passes through multiple regions, the sum of the digits on the line must be the same in each region); - Renban (the line contains a set of consecutive digits in any order with no repeats).