Normal 6x6 sudoku rules apply. Each digit in a circle indicates how many times that digit appears in a circle in the puzzle. Digits strictly never appear more than once in a cage. Cells separated by an X sum to 10. Not all possible Xs are given. Grey lines are palindromes, i.e. digits equidistant from a grey line's center are always the same. Those are all the rules. Do not forget any of them.