Really cool simple idea, with good execution. The physics feels nice, although the gravity felt a bit heavy. I assume it was done like that though, because otherwise it would be too easy. The extra features were a really nice touch, such as being able to load your own sources files. It would be nice if reaching the end of a file would either loop, or trigger some kind of file complete screen.
Overall, a neat idea with some great additional features to add to the game make it a fun nifty idea.