Normal sudoku rules apply. A black dot sits between two digits where one is double the other. Not all dots are necessarily given. The single grey line is a palindrome ie its digits read the same forwards and backwards. Blue lines in the grid are Region Sum Lines ie The 3x3 box borders divide each blue line into segments; each segment along a line has the same sum. (NB Different lines may have different sums). Eg r5c2+r5c3+r6c2+r6c3=r7c2+r8c2=r7c3+r8c3. The salmon coloured lines in the grid are entropic lines ie Any set of three sequential cells along an entropic line must contain a low digit (123), middle digit (456) and high digit (789). Digits may repeat on a line, if allowed by other rules.