Thanks a bunch for the detailed feedback!
We do have a bunch of more content that we would like to add (as you say, platforms, obstacles, etc), and some control and physics issues to fix, so your comments are spot-on.
For the lava being too slow, there is a bug (in-game) that will reset the lava position to your current screen, but we would definitely need to tune down those 'super-jumps' a bit if we make a more fleshed-out version.
Adding slow-mo feedback with the sfx and music is a great idea, thanks for that!