I like the concept of this game a lot. However, you could have gone so much further with it!
I did not like the music; I felt that the cave music did not suit, it sounded somewhat Arabic. As for the forest's music... Sure it's exciting and super frickin' happy, but golly gosh is it annoying. Also, may I suggest not having some of the characters' sound effects on loop next time? I did not like the abrupt ending either, I wish you dragged things out a little bit more.
I really like your style of illustration for the characters, especially for those who live in the cave. They look so interesting. I would have preferred if you had given the same amount to detail to the backgrounds as you did to those characters. The backgrounds of both the cave and forest were nice but you could have done so much more and really emphasised the physically friendly and unfriendly traits of the two places. I did like the simplistic look using only shades of grey and the red ball but again, the opposite traits of the two areas could have really been emphasised with colour - dark, gloomy colours for the cave and bright, vibrant ones for the forest.
I think you were clever to leave the protagonist with his appearance as neither typically good nor typically bad, too.
As I said, really like the concept but I think you could have and should have gone further with this. Would love to see more from you though!