Really impressive work! The main mechanic is pretty unique. I'll admit, at first I didn't find it super fun, but by the 3rd level it clicked and I enjoyed it a lot! I completed all the levels.
The GFX are great, and the SFX and music work well. It's got a nice atmosphere to it.
The only bugs I noticed were a 1 pixel gap in the BG clouds (I run into this problem a lot myself) and on one level a platform didn't reset after failing. Took a couple tries, but when I final hit it again, it went back to functioning normally.
Awesome game, I wouldn't have guessed it was a 48 hour (or less!) project based on the quality.