I like the calming coordinated visuals, but feel the basic concept is lacking originality. One of Mark's suggestions in the theme video was literally this exact concept, but applied to Tetris.
I also managed to glitch out the physics so I could move the level walls right through the box. Could have kept playing forever, as I could still collect the yellow target.
Congratulations on making something that works as a proper game in 48 hours. That's not a simple feat, I know!