Digits on arrows sum to the attached circles. Digits within cages can't repeat and sum to the small number in the corner. (or to an even/odd total for certain cages). This puzzle is solved in THREE stages: Stage 1: Each 3x3 box is solved independently as a 3x3 “mean mini”. (Each box uses exactly three digits from 1-9 without repeating in the rows or columns of that 3x3 box.) Stage 2: Delete all digits except for the central cell of each 3x3 box, then solve each 6x6 quadrant as a “Quattroquadri”. (Place the digits 1-9 once each into the 3x3 boxes such that they don't repeat within rows and columns of the 6x6 bold outlined region) Stage 3: Delete all digits except for the sixteen digits saved from Stage 1 and the central four cells of each quattroquadri; this should result in four small X shapes of givens in the grid. Each 12-cell row, each 12-cell column, and each 6x6 quattroquadri of four 3x3 boxes consists of three sudoku boxes and one mean-mini box. Each sudoku box contains the digits 1–9 once each. Among the sudoku boxes, digits cannot repeat in the grid’s rows nor columns. Each mean-mini box can be solved again as mean-minis with one doubler per row and column of the 3x3 box. The doublers don't have to contain different digits.