It's a little finicky and it took me a little while work out what I was doing but once I did the game felt pretty good to play. I think sound effects would add greatly, however. The art is nice and so is the colour scheme, I think perhaps a larger resolution and more detail would illustrate the transformation to rock a little better. The game isn't very long but neither is 48 hours. I think you've done a good job :)
The gimick is really quite fun and creative! Seeing the character in a void but still hearing the sound effects is really neat. The movement as a whole weren't too reliable though which takes away from the experience as a whole. The sliding and momentum were pretty cool but jumping off was also unreliable.
ps: The character turning monochrome as he closed his eyes looks very good.
