While on the surface it might look like little more than a very pretty first-person shooter, BioShock is much, much more than that. Sure, the action is fine, but its primary focus is its story, a sci-fi mystery that manages to feel retro and futuristic at the same time, and its characters, who convey most of the story via radio transmissions and audio logs that you're constantly stumbling upon as you wander around. All of it blends together to form a rich, interesting world that sucks you in right away and won't let go until you've figured out what, exactly, is going on in the undersea city of Rapture.

Rapture is an amazing city that sits at the bottom of the ocean, but something's gone horribly wrong down there.

BioShock opens with a bang, but the overall plot focuses more on making an emotional impact than an explosive one. The year is 1960, and you're flying over the Atlantic Ocean. One mysterious plane crash later, you're floating in the water, apparently the lone survivor, surrounded by the flaming wreckage of the aircraft. But there's a lighthouse on a tiny island just at the edge of your view. Who in their right mind would put a lighthouse this far out? You swim closer and discover a small submersible called a bathysphere waiting to take you underwater. After catching a breathtaking view of what's below, you're sent into the secret underwater city of Rapture. Masterminded by a somewhat megalomaniacal businessman named Andrew Ryan, this city is driven by its own idea of total freedom, with capitalism completely unhindered by governmental meddling and science unhinged from the pesky morals of organized religion. Sounds like the perfect society, right? Well, even before you step out of your bathysphere and into the city, it becomes obvious that everything has gone horribly wrong down here. The city is trashed, and genetic freaks called splicers roam around, attacking anything that gets in front of them. At the heart of the matter is a powerful, corrupting substance called ADAM, which makes all this genetic tinkering possible and allows you to get your first plasmid power, the ability to shoot lightning out of your fingertips.

Character customization is a key trait in BioShock. You have a limited but increasable number of spaces in various customization categories, and you can totally reconfigure all of your different plasmids and tonics at will, at no charge, at specific locations in-game. Plasmids are the active, weaponlike genetic enhancement. Many of these are very straightforward. Incinerate lets you burn things and melt ice. Telekinesis lets you use your left hand as if it were Half-Life 2's gravity gun. But others are a little more subversive. Security bullseye is a little ball you can toss at enemies, causing any nearby security cameras, turrets, or sentry bots to point in his direction. Enrage can cause enemies to fight one another. Insect swarm causes your arm to shoot bees at your enemies, which unfortunately is far less cool-looking than it sounds. You can also place decoys, plant swirling wind traps for enemies, and so on. While it's fun to mess around with a lot of the indirect attacks, facing your enemies head-on with the more direct plasmids feels a bit more effective.

Tonics are skills that are slotted just like plasmids, but they have passive effects, like sportboost, which increases your movement and melee attack speed, or natural camouflage, which makes you turn invisible if you stand still for a few seconds. So if you want to make your swinging wrench attacks more powerful, you can slot up things like wrench jockey and wrench lurker, which increase your wrench damage on all attacks and when catching opponents off-guard, respectively. Add bloodlust, which gives you some health back every time you club someone with your wrench, and you're a melee master with health and plasmid energy (called EVE) to spare. You can also slot some defensive stuff, like static field, which zaps anyone who touches you with a electric radius effect, and armored shell, which reduces the damage you take from physical attacks. There are more than 50 tonics to collect, giving you plenty of options to play around with.

ADAM and EVE combine to let you shoot fire, lightning, ice, wind, bees, and more out of your fingertips.

Most of those plasmids and tonics will have to be purchased using the raw ADAM that you collect from harvesting vessels called little sisters. They're little girls with a big needle that they use to collect the sought-after stuff from dead bodies, and they're protected by the baddest enemies in the entire game, hulking armored monsters called big daddies. This is where the game makes you decide to be selfless or selfish. If you harvest the girls, they die, but you get 160 ADAM from them. If you free them and return them to normal, you get only 80 ADAM. There are a limited number of girls to deal with in the entire game, making it very possible that you won't be able to collect every single purchasable plasmid and tonic, so choose wisely. Either route has benefits and consequences, and there are story considerations as well.

Before you start thinking this is some kind of role-playing game or something, let's stop right here and say that in addition to all the toys that plasmids and tonics for you to play around with, you're also going to be carrying around some more conventional firepower. Your melee weapon is a wrench, and you quickly collect a pistol and machine gun. Being that this is 1960 filtered through the isolation of an undersea world that has the art deco style of the first half of the century, the weapons aren't nearly as high-tech as the genetic code in your body. The machine gun is your basic tommy gun, and the grenade launcher appears to have been cobbled together from coffee cans and other spare parts. You'll also get a shotgun, a crossbow, and so on. You can also collect different types of ammunition, such as exploding buckshot for your shotgun or missiles for your grenade launcher, and upgrades that increase damage, speed up reloads, and so on. The weapons are functional and the upgrades are pretty good, but the firing action isn't nearly as exciting as a combat-focused first-person shooter would be. The weapons are loud but don't feel especially right, and seeing shotgun blasts not even do 50 percent damage to an unarmored human target (on the default difficulty setting) just feels wrong. But that might also say something about the general lack of enemy variety.