My code passed validation so I can't attach any code. I'm less concerned about validation than about the code making sense. I have added some simple println statements to get the two cells that are set. Here is one example with a screenshot of the board: When I test the values I get: gameField[1][0] = 2 gameField[3][3] = 2 This seems wrong. It should be gameField[0][1] that is = 2. X is for counting horizontal, y is for counting vertical, that's a standard. I've done programming in other languages and never done this grid inversion thing, and I don't understand why we're doing that at all.