Penhoat, I use a boolean array in my game to flag each level as complete or not. As you complete a level, the value is set to true and saved. At my level select menu, it checks to see if the level has been completed. If so, the next level is unlocked. Not sure if it’s the best way, but it works like a charm. Check the video series in my sig…I think video 12 shows the way mine is done.