Great stuff! The UI is polished, and the animations and sounds are presented well. I got through several levels.
Would have been great to have a rewind-one-turn button when you fall off, instead of needing to start again, and also a keyboard control for the popups like the restart level popup. There was one level where I got to the same point maybe five or six times, and for some reason couldn't help myself pressing the wrong directional button each of those times!
I'm not sure if this shows up after level 6 but: it would have been cool to see some more interesting dynamics that come from moving the level rather than all the penguins, so it's not a game about moving all the penguins at once with reversed controls.
It's also great that there's options for turning on and off the sound.