I think that this is the best game you made so far.
It's pretty fun but there are problems. The music is cool but the platforming is pretty bland and has no depth in it. I recommend you make some kind of puzzles within the platforming or something like that just too add a little more depth to it. The boss fight is strange because and not very fun because the hit boxes are just so strange. Also add some enemies. The lava level was frustrating because you just slided off the small platforms. The 2 player mode works pretty well.
Anyways keep trying :)