I think what you are asking for is more levels where no code is given, where you are challenged to complete the level using the skills that you were suppose to pickup.
I have been working on “review” levels for the game to allow one to go back over previously learned skills, I think I will add a second step called “mastery” levels that force the student to utilize these skills.
At first I had them combined, but it was deemed too difficult. Creating two paths would be beneficial.