I liked it = D

Considering this is a prototype has a good gameplay
Some things could be optimized
As the menu and all the graphics
You can add some animation when you win a level
The only thing of gameplay that could be improved is show an exact point where the lines must pass to win, because it´s very difficult to mark the exact point,
If it is made conscious to add some difficulty can be balanced by adding some item you can not get through, like a salt shaker a bottle or trash = P
Luck with your job