Ah I see what you mean maybe. Assuming you have level select object to click on, you can give this instance variable with a number. Then you can use a global variable for the player and it should match the level. So if you reached level 3 the variable is 3. Then on the level screen you lock all objects where instance variable is higher than the player variable, so anything with instance variable 4 or higher is locked, that would be my approach anyway. As for opening the game again with the progress, you would still need to make use of save game as mentioned above. You could save the game every time you enter the level select screen.