As I understand it, it's an expansion - presumed to be $20 - packaged with the original game. The total price would be $40. If my understanding is correct, that really pisses me off. I want the Dark Arisen expansion, but I'm not going to purchase the whole game again just to get it; I already own it! They're not releasing the expansion as DLC, which isn't surprising considering it's Capcom - the kings of the "Super Turbo" edition.
If I'm misunderstanding the way they're releasing the Dark Arisen expansion, I'd love to hear how I can get the expansion for $20 stand alone.