Normal sudoku rules apply. Any two orthogonally adjacent cells cannot contain digits in a 1:2, 1:3, 1:4 or 1:5 ratio. Every horizontal set of three orthogonally connected cells within any 3x3 box is a modular sequence (i.e. must contain one digit from [1 4 7], one digit from [2 5 8] and one digit from [3 6 9]). Every vertical set of three orthogonally connected cells within any 3x3 box is an entropic sequence (i.e. must contain one digit from [1 2 3], one digit from [4 5 6] and one digit from [7 8 9]). There are no 3's in a corner of the grid.