Normal sudoku rules apply. Each of the following standard clue types occurs exactly three times in the grid: Arrow, Circle, Dots, Odd/Even, X/V and Zipper . For each of those clue types, exactly two of the appearances of that clue are correct and the other is incorrect. The "standard" clue types mentioned above are as follows: White dots: Cells separated by a white dot must contain consecutive digits. Black dots: Cells separated by a black dot must be in the ratio of 1:2 (so one digit must be double the other). Arrow: Digits on an arrow must sum to the digit in that arrow's grey circle. Xs: Cells separated by an X must contain digits summing to 10. Vs: Cells separated by a V must contain digits summing to 5. Odds: Cells containing an opaque grey circle must contain an odd digit. Evens: Cells containing an opaque grey square must contain an even digit. Circle: A digit in a purple circle indicates exactly how many purple circles contain that digit. Zipper: digits an equal distance from the centre of a blue line must sum to the digit in the middle of that line.