Normal sudoku rules apply. Digits along the green Christmas tree line alternate between odd and even numbers. Digits along an arrow must sum to the digit in the connecting circle. (The bottom two arrows represent garland and the top arrow is a star.) Digits connected by a white Kropki dot must be consecutive. (These represent tree lights.) The digit in the large quadruple circle must be in at least one of the four connecting cells. (This represents a large ornament.) And the gray square at the base of the tree is an even digit. (This represents the tree stand.)