**Before you are saddened by my beating this without you, note this: I want to go through it again.**
I finally sat down and beat Castle Crashers. Matt, Chue, and Sean had already gone through by themselves and defeated the final boss. Ztynzo offered to sit down with a secondary character and help me finish the main campaign.
I say finish the main campaign b/c Castle Crashers is hardly over after the final boss goes down.