Just before putting the 2 in here (above the pencil 6), I put in 6 and it said Mistake, so I erased it and put 2. But... why wouldn't 6 be valid there?
EDIT: As per replies, "X" Sudoku is variant with a different rule. While I saw the diagonals "highlighted" in another color, I didn't know that rule. Perhaps it could be added to the page for those unfamiliar with this non-standard Sudoku variant?
Because there's already another 6 on the same main diagonal. This is an "X Sudoku" puzzle, which means that each main diagonal must have all 9 different numbers.
if you like sudoku, you owe it to yourself to check out the "cracking the cryptic" youtube channel and get introduced to the delightful world of variant sudoku.
Just before putting the 2 in here (above the pencil 6), I put in 6 and it said Mistake, so I erased it and put 2. But... why wouldn't 6 be valid there?
https://imgur.com/a/aOnKbiT
EDIT: As per replies, "X" Sudoku is variant with a different rule. While I saw the diagonals "highlighted" in another color, I didn't know that rule. Perhaps it could be added to the page for those unfamiliar with this non-standard Sudoku variant?