Only thing lacking is an understanding of how stars are achieved. If it’s based on items used, assign them each a dollar value (eg, wheels are $100) and then set a budget for each level (eg, $500 spent = 3 stars, $650 = 2 stars, etc.). If it’s based on time, tell the user what to strive for (eg, 10 sec or less = 3 stars). Because right now I have now idea why I’m getting 1 star on some and 3 stars on others.
Also - users need the ability to replay the intro / how-to. (I don’t know the difference between the solid and dashed lines, and would like to go back and view the demo again.)