Solid game - from a gameplay standpoint, I think this game is solid and knows exactly what it wants to be - kudos! But, I feel like this game is a little stiff. You have a hamster guy and you have aliens, but I don't sense their personalities. This may be an unusual bit of feedback, but when a hamster goes into space, I imagine some unusual things to happen, but the aliens looked run-of-the-mill to me. Don't get me wrong - the art was fantastic and well-executed, but I think it lacks personality and I think that takes away from what motivated me to play this game. Make it a little weird, go crazy! That's my thoughts, anyways.
Also, about the music - you chose a good track! It fits well and it never got annoying despite its short length. I would have liked if you selected a few more and had multiple selections fading in to each other, just to liven things up.
Ultimately, great work - keep it up!