Really enjoyed conquering the volcano! I thought the ending screen and the graphics in general were extremely charming, but what impressed me most was the level design - it actually showed a very good understanding of providing challenge with the overall quite simple mechanics and at least from what I can tell, basically fully explored what is possible with them. Good work!
The only criticism I have is that sometimes the double jump would randomly not work for me - there's probably some annoying bug hiding somewhere, but I know how frustrating finding something like that is, when I'm not even sure what causes it.
Keep up the good work!