Normal sudoku rules apply. Correctly placed digits clear the fog around them. Along an orange line, neighboring digits must differ by at least 4. A purple line contains a non-repeating set of consecutive digits in any order. A digit inside a white circle must appear in one of the four cells surrounding that circle. Each circle contains four distinct digits, which are listed from smallest to largest (left to right and top to bottom). These digits can appear in any order around the circle.