Fun premise, good movement! Needs some work on the execution, but you did a good job regardless :)
Getting up in the clouds was too difficult for me. I was unsure whether I was supposed to use the updraft of the volcano or the ramps at the bottom. The camera angles made it a bit hard to aim my drop when floating above the volcano, and I couldn't seem to keep my momentum when rolling down trying to hit the ramp.
I appreciate the music changing pace depending on how fast you're going, that's a nice touch. Reading your previous comment I can see you had a lot planned. I hope you won't be dissuaded by not achieving all your goals and that you learned a lot too. Overall a fun lil' jam prototype, keep it up!
P.S.: Remember you can do a WebGL export when using Unity. A lot more people will play your entry when there's a web version of it available!