Another Soul Calibur 3 one: In the story mode, each character has a specific route they can take, which will lead to them entering a labyrinth, fighting their story-determined enemy, fighting an "Unknown Soul" who is shrouded in darkness, and then fighting the new character Olcadan, who uses a random fighting style and is very hard to beat. If you manage all of this without losing one battle, you won't fight Abyss at the end, you'll fight the much tougher Night Terror--who is much more of a traditional fighting game boss in that he cheats, has unblockable "lose half your health" moves and is generally cheap as all hell.
The three "Unknown Souls" are actually characters from the earlier games who didn't make the final roster--Arthur, Li Long and Hwang, using the generic fighting styles.
Devil May Cry was originally meant to be a new Resident Evil game, with the puppets originally being zombies.