Sequels are hard. Whether it's a game or a film, there's always the chance that following up the first act will end badly and ruin the franchise, such as what happened with "Robocop 2." On the other hand, they could become spectacular successes, like when James Cameron decided to send marines into space in "Aliens" or revisit genocidal AIs with "Terminator 2."

BioShock had also ended on a note that could have been left alone but an underwater dystopia seemed too perfect a place to not revisit with another story, and that's exactly what BioShock 2 dares to do. It's a trip back to the city of Rapture 10 years later, and the lights are still on.

But first, a word about Games for Windows Live. This is the service that the game requires and will install, and since I experienced it with Fallout 3, it hasn't done much to change my impression that it's something better served on the Xbox 360 than the PC. If I didn't already have an account set up for this, I would've had to make one just to play. After all that, you still have to keep the disc in the drive, and it'll automatically download patches, which are mandatory for online play. There's no way to opt out of those if you simply want to hop online for a quick game.

BioShock 2's story is set up so that players who didn't play the original game can dive in without knowing exactly what had happened, although some of the impact in seeing and hearing certain things may be lost. This is a game that easily caters to fans who had survived splicing their way through Rapture's enclosed underwater streets and alleyways the first time around. Newcomers won't have to worry about which ending occurred in the original game, leaving it up to everyone to decide whether the player had escaped as a survivor or as a saint. Rapture's condition is still the same: a city slowly dying from within as the ocean continues to find its way inside.

This time, players star as a Big Daddy, an engineered giant of armored might assigned to protect ghoulish Little Sisters. Even though you were one of the first, you're supposed to be dead ... until someone brings you back 10 years later. Now, with only the memory of the Little Sister who you had once protected, you must head into what is left of the city of Rapture to rescue her and find out why you were brought back.

The manual does its part to bring newcomers up to speed on events. Veterans will need little introduction about what they can expect, but the story paints carefully within the lines established by the original title, respectfully following the legacy almost to the point of sometimes feeling stifled.

Revisiting Rapture with its 1950s-inspired music and visual ambiance is just as good as the first time, though the story takes on a decidedly different focus in BioShock 2. Instead of the philosophical tug-of-war that sowed the seeds of conflict between two mighty giants in the first game, the sequel focuses much of its time on a Big Daddy's quest to find and protect his assigned Little Sister; this lends a different, but welcome, feel to this chapter.

All of this is set against the backdrop of seeing Andrew Ryan's vision of the city through the lens of someone who had very different ideas about individuality. On the whole, it comes off as more of a revelatory piece, giving fans a fresh and deeper look at the rest of Rapture's downfall as well as its major players. It's a theme park of ideas that might have made it into the first game.

The story is also told through tape recorders, which are scattered throughout what's left of the city, and I spent quite a bit more time than I probably should have in trying to track down each one. Even the endings, both good and evil, have been given a lot more screen time. They certainly feel far more rewarding and ominously darker than the canned finales of the original title. Although they don't quite capture every nuance of the decisions that you make, the final sequence ties up the story in a very satisfying way, making both the journey and the destination equally strong.

The title also has a few odd shortcomings, not the least of which is that the passage of 10 years hasn't seemed to change Rapture, or its people, all that much, almost as if it were thrown in to explain how old certain antagonists had become. There's also more linearity in how it progresses from area to area, and players who don't collect the tape recorders will miss out on much of the storied tapestry. Each area is treated as a large level filled with plenty of ruined lives and hidden secrets, providing plenty of the lived-in atmosphere of Rapture. Once the area is solved and then left behind, however, there's no way to return to and revisit earlier zones in case they might have missed something, unlike the original game. If you lose out on any tape recordings, special plasmids or tonics before you leave, don't expect to come back to try again.

Looking at the interface options, the game doesn't support control pads, which is a big surprise because some other games on the PC do. Widescreen support also inherited a bug that was present in the first game, which 2K has promised to patch. Players can also change the difficulty level on the fly and disable the massive number of visual aids that pop up on-screen, such as an arrow pointing the way to the next objective or tooltips that appear when pointing at items of interest, of which there are many. To add to the challenge, you can also disable Vita Chambers — special pods that can resurrect you if you die — which are scattered throughout each area.

Even as a Big Daddy, it's not all sunshine, rose petals and drills. You're not a newer model like Bouncer or Rosie, but you can think on your own and use a number of different weapons, including valuable plasmids that act as genetic super-powers, as you have the EVE to fuel them. As with the first BioShock, the options that can be explored with its repertoire of powerful plasmids and lead-spitting weapons to burn, shatter, electrify, perforate and blow up whoever is in the way is still very much a part of the gameplay, pushing me to invent new ways to end the lives of the many Splicers that come calling. BioShock isn't so much of a pure FPS as it is an urban exploration game set within an apocalypse under the sea.

Then there are the tonics, genetic enhancements that provide a passive bonus, such as exploding in an electrical field when someone's fist enters your personal space. Like plasmids, they must be found or purchased with precious ADAM, a substance secreted by special sea slugs that live on the ocean floor near the city. ADAM is also what brought Rapture to its knees, and the best source of ADAM are the Little Sisters who go around with giant needles, draw the blood from special corpses that have it, and distill it by drinking it. This also plays right into the Big Daddy role.

As a Big Daddy, I can adopt a Little Sister to help her harvest specific corpses for ADAM. But to get to one, I also had to kill another Big Daddy. It's a lot easier to do that as a Big Daddy than it was in the first game, but the aftermath underlines why it can also be bad to be a Big Daddy.

Splicers, the less-than-human remnants of those who had played with their genes well past their expiration date, also want ADAM to survive. They also know that Little Sisters are the only source, so as soon as they find one in harvest mode, they'll do almost anything to grab her. That's where you, as the Big Daddy, can come in as an avenging angel to defend your Little Sister while she does her thing. She can't die, given that she has an ADAM-producing sea slug in her that keeps her essentially immortal, but you can. The Splicers' favorite tactic is to swarm like hornets, making these moments some of the more intense in the game as you set traps, find a spot to cover the Little Sister while she does her thing, and then wreak havoc on whatever comes near.

On the other hand, if you don't want to go through these harvesting sessions, you face a moral choice, and unlike the first title, it has bigger repercussions on one of the title's more personal storytelling elements, especially with the ending.

Eventually, you'll have to face off against a Big Sister whose lethal gymnastics can easily run circles around anything you throw at them. Big Sisters are mini-bosses peppered throughout the game, and they're just like you: armored from head to toe and able to use plasmids. Big Daddies are yesterday's model compared to these.

Extra plasmids and tonics can also be stored until you decide to use them in replacing an existing power or having more slots to assign them to, but ordering them around was a pain. Although you can use a Gene Bank to assign genetic enhancements to open or filled slots, you can't re-order things, which would have been handy with plasmids. I would've wanted to organize my plasmids into a certain order, but the only way to do that was to buy up more plasmids and then play "swap the plasmid" with the extras to get things the way I wanted, or remap the keys.

It also didn't help that the menu would sometimes turn into a mess of elements where nothing was supposed to be. To listen to previous radio messages or discovered tapes, as one example, I'd have to "guesstimate" where the buttons were because they no longer corresponded on-screen with the actual graphics. Other weirdness included Big Daddies occasionally ignoring accidental attacks from everyone else other than me and a bizarre issue with a "befriended" Splicer who beat on an ally during an in-game cinematic. The game ran as smooth as Plexiglas despite the weirdness.

For hacking things to do your bidding, I didn't mind the pipe game too much from the first, but its replacement isn't that much better. Although it does away with the pipes, it replaces it with a timed reflex exercise that gets boring after awhile as you try to stop a needle on a "hot spot" before moving to the next round to do the same thing again. It's different but actually felt less engaging than the pipe puzzle.

The first BioShock didn't need multiplayer, perhaps taking a cue from Andrew Ryan's cult of individuality with its focus on the single-player experience. In today's FPS market, having the option to take that action and rub it in someone's face has almost become a given. The debates over its storytelling elements muted the questions over multiplayer, but with the sequel, the answers are better than expected.

Digital Extremes, perhaps best known for its work with the Unreal Tournament series on PCs, helped integrate multiplayer with the world of Rapture. Fortunately for players, it isn't a "tacked on" experience that feels like it's been added at the last minute. Although the game types aren't revolutionary, each one has been given a distinctly Rapturized flavor. Capture the Flag now becomes Capture the Sister, where you must find and steal the Little Sister on the level and take her to the nearest vent to score. Team Deathmatch becomes Civil War, and Headquarters becomes Turf War. The journey doesn't quite end with the single-player game and is aimed directly at the fans who clamored for it.

A word of caution: If multiplayer is all that they want out of the game, some players will find its multiplayer to be a different experience, though they'll also have to decide whether or not its flavor will make them permanent guests. It's different in the way that Might and Magic: Dark Messiah's magically powered multi is different from Modern Warfare 2. Is it fun? Absolutely.

Multiplayer is treated as a creative extension of Rapture's story by bringing players into the civil war that tore apart the city in 1959, roughly 10 years before the beginning of the sequel. Everyone is fighting for ADAM, and Andrew Ryan and the rebellious Atlas have their followers burning the streets — and each other — to get the upper hand. Fans who are familiar with the lore will probably get more mileage out of this than those who are jumping into the fight for the first time, although the gameplay has a few tricks to keep them coming back for more.

Players are enrolled in Sinclaire Solutions' testing program, explaining how they get to use weapons and plasmids supplied by the company to wage battle across Rapture. An apartment is even provided as a great atmospheric piece that also serves as a visual menu for players to change their character's appearance. When they're ready to go, they can take a bathysphere out to the player lobby. Of course, all of this is optional stuff. The next time the player starts up MP, he can just head to the lobby and straight into the action.

Maps are pulled from the first BioShock, since this takes place during the war that ripped apart Rapture, making this feel like a homecoming of sorts. Most of the maps have been reconfigured into MP-friendly versions but retain much of their general layout, so if you remember Arcadia's gardens, welcome back. For newcomers, the relatively compact maps offer plenty of hiding spots, alternate ways to get to objectives, vertical vantages, choke points for ambushes, and glorious booby traps.

BioShock's gameplay has translated relatively well to MP. Players can use weapons and plasmids, and tonics are also available for special boosts, such as faster health regeneration or being able to deal increased melee damage if you sneak up behind someone. Customized loadouts are also open for players to tinker with, and if one isn't working out, you can always opt for something else while waiting to respawn. If players are lucky, certain modes will spawn Big Daddy suits for fleet-footed Splicers to snag and mow down opponents.

BioShock 2's MP employs the same leveling method that Modern Warfare does with experience doled out for kills and completed objectives. Players start out with only the basics and a tiny handful of open slots for their initial loadout. As they gain experience and earn levels, more items become unlocked such as additional plasmids, tonics, new weapon modifications, and loadout slots making continued play fairly compelling.

Players can also hack turrets to target enemy players, booby-trap vending machines to deliver explosive surprises, and even take humiliating research pictures of fallen opponents to earn a damage bonus. Mixing up heavy weapons with magical plasmid powers to lay traps or get the drop on enemies with teleportation can be extremely fun, especially with a good team on your side. Although player counts are small in MP and many of its modes only support a maximum of 10 players, the furious action often sets the pace.

While the atmosphere and gameplay are over-the-top, it's hard to not notice the console-inspired touches. Most of my time was spent passively waiting in a lobby for games to show up, since it supports automatching. Instead of being able to actively poke through a list of available games, waiting for the random chance to join an active game type is about as much fun as re-ordering my loadout for the umpteenth time.

You also can't change teams, and this can easily screw over players when half of their fellows decide to jump ship or if you want to hop over to help one that needs an extra body. There's no logic to the balancing, either, as I've often been assigned to teams whose members were already at level 15+ versus a team of newbies who had just gotten the game.

BioShock 2 is still worth the price of admission to Rapture. Although it feels far more action-packed and is more of a linear submarine ride into the deep blue than the original title, what it does exceptionally well is bringing even more of Rapture's storied existence to the surface for some closure. The familiar gameplay doesn't veer too far from the original, which is both good and bad. It's good because it's familiar, but it's also worrisome considering that it occasionally felt more like an expansion pack. BioShock 2 is a unique story that pleasantly adds to the existing mythos instead of upending what came before "just because." By the time I came up for air at the end, I still wanted to keep diving back for more.

Score: 8.5/10