Normal sudoku rules apply. The line is an “equal sums” line, meaning that digits on the line have an equal sum, N, within each 3x3 box through which it passes. So, for example, r4c2+r5c2+r6c2 = r4c8+r5c8+r5c7. Cells separated by a black dot must contain digits in a ratio of 1:2 (ie one digit has double the value of the other). There are nine 'quintupler' cells in the grid, coloured red. They contain the digits 1-9 exactly once each, and occupy exactly one position in each row, column and 3x3 box. For the purpose of any arithmetic calculations, digits in quintupler cells count as five times the digit's value.