Normal 6x6 sudoku rules apply within the 6x6 grid. (ie place the digits 1-6, once each, in every row, column and 2x3 box.) Cells outside the grid contain “skyscraper clues”, which indicate the number of digits “visible” in that direction in the 6x6 grid (where higher digits block the view of lower digits). Eg a row reading 216453 would have a clue of 2 from the left (as the 2 and 6 would be visible); and a clue of 3 from the right (as the 3, 5 and 6 would be visible). Each cage sum is the same, and digits may repeat within a cage. Digits in cells separated by a gold dot are not consecutive. (The "solution checker" does not consider the skyscraper clues outside the grid.)