Normal sudoku rules apply. In each row, column and box there is exactly one 'pseudo cell.' The digits 1-9 each appear once in a pseudo cell. The real value of a pseudo cell (for the purposes of the coloured lines) is determined by multiplying its row number by its column number. Eg; if there is a pseudo cell in r6c3, it has the value of 18, regardless of which digit appears in that cell.