Normal sudoku rules apply. Orange lines are both index lines and entropic lines. Index lines: starting with the diamond at position 1, the digit at position N along the line indicates the position of the digit N on the line. Entropic lines: every set of 3 consecutive digits along the line contain one low digit (1,2,3), one medium digit (4,5,6) and one high digit (7,8,9). The arrow points to the smaller of the digits in the cells it occupies.