Neat idea! In practice the scaling was more of a time limit than a real obstacle; it would have been neat if there were things you could only go through if you were a certain size. I liked how you mixed it up with the twists on the levels, although I think the size bar was out of sync with the maximum size you could be to get through the portal. There were times I got to the portal before the bar filled up and I couldn't go through.
Good work!