I have my Steel Battalion controller, which was required for the game. Best controller and gaming experience I have ever had. Worth every penny.

But does that count as a third party controller, especially since it can only play one game?

It's technically 3rd party since it was not made by Microsoft. It also could be used in the follow-up to Steel Battalion, though wasn't required for it so it was at least useful for 2 games :P

I wish I kept mine. I could have converted it to a PC device quite easily.