Arrow: Digits along an arrow much sum to the digit in the connected circle.
Between Lines: Each digit on a line must have a value strictly between the digits in the circles at the ends of the line.
Anti-Knight: Cells separated by a chess knight's move may not contain the same digit.
f-puzzles: https://f-puzzles.com/?id=ygrzhwco
CTC: https://tinyurl.com/yf4u5xed
Solution code: Row 5 + Column 6 (18 digits)