Fun idea! I did get stuck inside a single open space, however. Might be nice if the hit box size was the size of 1 segment of a tetromino so you could fit through tight squeezes. I felt the controls were too slippery so it was too hard to just move over one segment length. I wish there was some more telegraphing that the pieces were about to go into slam-mode so I could plan a bit more.
Overall, a neat idea that I wanted to play more. Definitely worthy of post-jam pursuits!