Fun sandbox! Great idea, I've always enjoyed watching ant trails but hated the fact that they were there in my kitchen :P. Some suggestions: instead of just a +100 ant button, make multiple (+100, +500, +1000, etc), and adding things like walls or other obstacles for the ants to get around, or hazards that can kill ants (that one's a maybe), would be very fun for this sandbox.
The song was an original piece composed for the short "The Yuyu" by Adam Phillips. You can watch said short here --->http://bitey.com/2006/05/the-yuyu/
The entire thing is just this song, with some awesome action set to it (not the other way around).
Another handy feature would be a high score based on score per second, as in being recognized for making insanely high scores in short amounts of time.
To get past final level, you simply need to hold the right button while mashing the up button to commit suicide right off the cliff, and keep mashing the up and holding the right for a few seconds after you fall off the cliff, then restarting like that over and over and over. Eventually either you or a shadow will reach the door.
 "Viricide"){kind=icon}
 "Ants - Now with even more Ants"){kind=icon}
 "Flight"){kind=icon}
 "Haiku Hero"){kind=icon}
 "Dance of the Robots"){kind=icon}
 "Solipskier"){kind=icon}
 "Balloon in a Wasteland"){kind=icon}
 "The Company of Myself"){kind=icon}
 "The Best Game Ever"){kind=icon}
 "GeoSketch"){kind=icon}
 "Simplicity"){kind=icon}
 "Thing-Thing Arena 3"){kind=icon}
 "Death Dice Overdose"){kind=icon}
 "Bars of Black and White"){kind=icon}
 "BubbleQuod"){kind=icon}
 "You Have To Burn The Rope"){kind=icon}
 "Portal Wars"){kind=icon}