With the next BioShock taking to the skies, it’d be easy to write off Rapture. But please don’t — at least, not until you’ve finished this last, irresistible tour of the underwater city.

The single-player scenario in Minerva’s Den is set in a giant area we’ve never seen: Central Computing, where two of the colony’s finest minds, Porter and Wahl, crafted an A.I. of extraordinary brilliance. It’s 1968, circa BioShock 2, and as Subject Sigma — a Delta-like Big Daddy — you’re searching for this A.I. to help Porter and the returning Dr. Tenenbaum escape Rapture.

Naturally, you’ll encounter plenty of Little Sisters, Big Daddies, and Splicers as you go. The latter make great fodder for your new Ion Laser, but even the new Daddy (the Lancer) wilts beneath its devastating beam. Gravity Well, a new plasmid that forms mini black holes, is mildly fun, but like BioShock 2, the best part of this $10 DLC is its ending. The five-hour journey drags during its fetch-questy bits, but its finale — where your real goal, and purpose, become clear — is just perfect. Moving, melancholy, and even a bit hopeful, it’s a true stunner; don’t be surprised if it leaves you a little teary-eyed.

On Xbox Live Marketplace

+ Story is a worthy extension of the mythos, punctuated by a haunting, memorable conclusion.

+ New Ion Laser is a good Splicer- (and everything-) killer.

- Slow middle portion may lose some players; fundamentally, it's more of the same.

? Is this our last visit to Ryan's ocean metropolis?

8.0