This was incredibly fun! I was skeptical about 90-degree turns at first, but it ended up working very well with the physics engine; I just wish the turning was a little quicker. I was impressed by how many levels there were, since they all expanded on the core mechanics progressively. The game especially starts to excel once you aren't confined inside the walls anymore. The only minor gripe I have with the levels is that the difficulty curve is a bit uneven, since it gets progressively harder before getting easier by the end. That's only a mild inconvenience in a single sitting where you don't know when the game ends. With a level select/world system, it doesn't really matter much.