public boolean checkMainDiagonal() {
        //upper left to lower right (main diagonal)
        for (int col = 0; col < numColumns - 3; col++) {
            for (int row = 0; row < numRows - 3; row++) {
                int curr = gameGrid[col][row].getState();
                if (curr > 0
                        && curr == gameGrid[col + 1][row + 1].getState() //increment the column
                        && curr == gameGrid[col + 2][row + 2].getState() //and the row by equal
                        && curr == gameGrid[col + 3][row + 3].getState()) //amounts and get the state
                {
                    winX = col;
                    winY = row;
                    game.setGameIsOver(true);
                    return true;
                }
            }
        }
        return false;
    }