Quote: "Where? I can't find the option to add more levels to the standalone."
You cant add them to the standalone and probably never will be able to .... Each end of level triggers the next so this would have to be done when developing your game...... Create your game and levels before you create the standalone and If you wanted to add more levels in the future then it would be a case of loading your original game back into GG and expanding it there.....Although.... I guess there are ways around that if you used a custom launcher and a few tricks so each level was its own standalone ..
This video will show you the process of Multi Levels when making your game ..
The only person ever to get all his work done by "Friday" was Robinson Crusoe..