With infinite variation, this is really an infinitely fun game! I thought the grind would get boring, and the levels of gold required to unlock new characters or upgrades insanely high, but once you've played a few rounds it all feels balanced, and refreshingly well-paced. The numbers never soar disproportionately after you play to a certain point, but follow your progress, and I like how the unlockable characters rise in price the more you unlock, making the select few you choose a bit more special. Though, the yellow bird and demon are the only two characters I'd have liked to unlock, the others look more like foes than players.
One detail: I thought the fireballs were fire, and there was some bug with that medal before I reached the upper levels. With a 'die by x' medal for all elements, it feels like the projectiles are left out, as are the enemies. The reward for the crown-wielding ones feels a bit unfair as well, as they're often in spots where they're hard to bounce on repeatedly, and thus often harder to get than all other types.
Overall though, it was a both rewarding, and very addicting game, and both gameplay and graphics feel polished and smooth. Nice work.
-cd-