Neat game! The control scheme was charmingly novel at first, I don't think I've quite see anything like it before.
As the game went on, though, I realized it was very easy to just spam click in the general area I wanted the pen to move towards, so I mostly ignored the size mechanic by the end.
Those last two levels were devilishly long!! I'm not sure if they had any checkpoints in them as I first-tried both of them, but I definitely would have quit if I touched a meteor and had to restart. Funnily enough it made for quite the tense, enriching experience to feel like I only had one life going through the levels; specifically that last segment at the end of the last level where you're drifting through a 2-block tall hallway with meteors on both sides. Fun stuff!