[Sequels often get penalized if they don't change enough, but Gamasutra news director Leigh Alexander examines BioShock 2 to find an interesting challenge -- and opportunity -- in keeping some things the same.]

The main reservation critics and fans seem to have about the largely-acclaimed BioShock 2 is that it doesn't bring much new to the table, a conservative sequel to a game that didn't really need a sequel.

Wired's Chris Kohler said the game was "stamping on well-trod ground," and Game Informer's Andrew Reiner said the dystopia of Rapture had developed "the familiarity of a local shopping mall." The innovation of Rapture as a setting was part of what made the original BioShock so exciting, and now that players are used to it, the game loses something, some say.

Another recent release, No More Heroes 2, was also said to have been unnecessary -- director Suda51 himself has said he hadn't planned on tacking a sequel on to the story of Travis Touchdown.

Why do games that "don't need sequels" get them? The answer's obvious: the game industry's more hit-driven than ever, and it's no longer enough to make a successful game -- publishers need successful franchises. This leaves two options: conceive every game as open-ended, always setting up for a sequel, or attach sequels to games that "don't need them."

Neither sounds very appealing at first blush. But the major rush to sequelize even those titles that make solid self-contained experiences could create, by necessity, a promising shift in the way developers build worlds and innovate in them.

Although fans were quick to note that that BioShock 2 didn't feel much different from its predecessor, 2K was wise with it. The original title was so strongly received that to significantly change much about it could have been disastrous. Fans loved BioShock for its unique and deeply-realized world and the signatures that populated it: Madness, decay, philosophical frenzy, and the strange energy system governed by the eerie Little Sisters and their hulking protectors.

There's even very little room to improve on the game mechanics. They can be iterated upon, as with the welcome tweak to the hacking minigame, but BioShock's gameplay is well-established and part of its appeal. So much about the game identifies it distinctly that there isn't much that can be changed in a sequel -- there are too many elements without which it wouldn't be itself. But that's not a problem: That's a success and an opportunity.

BioShock is not just a stand-alone narrative. It's a framework. Rapture isn't the story, it's the story's housing. The lamp-eyed Little Sisters and lumbering Big Daddies aren't characters, they're elements of the visual language. Thinking about a sequel for a game with such a strong signature, it becomes clear that its key elements are signposts for the experience, and not the entirety of the experience itself.

And with the framework so distinctive and so firmly-established, there's a unique chance to evolve the expectations of gamers. Where BioShock presented one character of an only loosely-known identity with an objectivist despot as adversary, BioShock 2 presents the same sort of character and an enemy adherent to a different philosophy.

What can BioShock 3 do? It can't change Rapture's look, its citizenry, its rules or even meaningfully change the experience of interacting with the world. But it can present a new quest for self and a new philosophy to test within Rapture's mad power vacuum. In other words, it has no choice but to iterate on story and theme, and this fashion of approaching game franchises will only make gaming richer as developers get better and better at it.

It will be interesting if games start to become franchises by building a strong universe and desirable mechanics first, and then yield sequels that don't overhaul those things, rewrite the design mechanics or tack on new features where none are really needed just so gamers won't complain there's nothing new.

The result will be a new kind of sequelization. BioShock 2 returned us to Rapture in the best way possible: By simply creating a new adventure therein and a new way to look at familiar things. It's perplexing to see critics penalize a game for declining to change what they best loved about it.