I saw your post at Game Journals,about someone copying your game and at first i was thinking on issues like Mario vs Giana sisters,or Crush the Castle vs Angry Birds,but now when i see what this jerk did,...,wow.
And i am really not sure why are you going easy on him now:
" I'm not going to pursue it too hard, except ask him to remove the soundtrack and make a few more changes to the art. "
If it is true that he is newbie,like he said,that lame excuse doesnt give him right to keep on doing it.
If there is some way to remove or block his game until he changes all the art not to resemble yours,than let him do that and that way he can show that he understands the copyright issues and is honest.
Other than that i dont see how he can stop doing this again next time,and maybe he hits some jackpot with stealing someones work.
Just to say I am not fan of birds games,and the hype they make.
I am even developing some parody on them,but this is something completely different.
Resemblance is too obvious,features,mechanics,gameplay,colors,music,...,and it can not be coincidence.