Gotta say that I love the soundtrack in this game!
It's a fairly interesting game, with a fairly nice art style. To be honest, I did go through the first couple of levels without realizing I could collect matter from buildings and goats, but I should have read the description more carefully. I did initially think that matter was a bonus you got after completing the level. I think you nailed the enemy variety and it had a pretty good skill curve, although the enemy that jumped over buildings caught me more times than not. It was definitely a challenging game, but it was a fun one.