Quote Originally Posted by boatofcar View Post
According to the Retronauts podcast, TMNT II also used a special chip, mostly for the iron balls that bounced down the stairs in the first level. If you go back and look at them, that animation in itself darn impressive for a NES game, and it's not hard to see why a special chip would be required.
Of course TMNT II used a special chip. Almost every NES game did.

Check out this page:

The Games That Pushed The Limits Of The NES