I think the game at least needs feedback sounds for hitting and missing the arrow. I did not even realize the first time playing that missing means losing one life. Give the player some more rewards!
Nice idea, but the collision detection seems to be based on rectangles instead of bubbles, which makes trying to avoid the bigger bubbles pretty frustrating.
I played gamma bros before when reading about it on gamasutra and I totally underestimated it the first time... Hell, why? It is totally awesome! Hope you guys will be one of the finalists at the Independent Games Festival in San Francisco.
The idea is actually borrowed from the great Calvin & Hobbes cartoons: The game design is based on the fact that kids often make up new rules and change them while they are playing.