The floatiness felt good for this type of game, and I liked how it controlled underwater where you actually floated due to how light you are. The phase mechanic is cool, though I would have liked to see the exploration have more routes to and from things since it took some time to backtrack though a large number of lights towards the exit and the phase didn't last long enough to take a shortcut back even when upgraded.
Overall a neat concept that has room to expand!