Logic Masters Deutschland e.V.

(This is one of a series of puzzles using the entropic/modular constraint. If you like it, give the others a try! Deadlines, Guidelines, Hotlines, Triplines)

Place the digits 1-9 once into each row, column, and 3x3 box. Digits along an arrow must sum to the digit in the arrow's circle, and may repeat if otherwise allowed. Digits may not repeat along either diagonal.

Each row and each column is either an entropic line or a modular line. On an entropic line, each set of three consecutive digits must contain a low (123), middle (456), and high (789) digit. On a modular line, each set of three consecutive digits must contain one equivalent to 1 mod 3 (147), one equivalent to 2 mod 3 (258), and one divisible by 3 (369).

(Lines of the same type that cross are considered separate lines. E.g. if row 1 and column 1 were both entropic, R1C2 and R2C1 could both be low since they're on separate lines.)

Online solver: SudokuPad