What happens in between, from your formative years in the shelter of Vault 101 and well beyond your eventual escape into the irradiated, postapocalyptic Wild West outside, evolves via a nice mix of guided narrative and player choice. Help a townsperson kick his drug habit and you'll earn good karma; feast on the corpses of your enemies in broad daylight, on the other hand, and people might think you're a little weird. How you deal with the challenges of the Capital Wasteland affects what nonplayer characters will fight by your side, where your early quest-hub town is, and also some details about the game's final chapter.

But it's not just wanderlust and the search for your on-the-run scientist dad that compels you forward in Fallout. Like any RPG, character advancement is both a means and an end. While the leveling system in developer Bethesda's previous game, The Elder Scrolls IV: Oblivion, was built on an arcane combination of attributes, skills, skill perks, specializations, and multiple class templates, Fallout 3's mechanics are far simpler and far improved. You allot your attribute points at the beginning of the game, and when you gain a level, you earn a certain amount of points to spend on skills (Speech, Lockpick, Energy Weapons, etc.) and one perk of your choice. Perks range from practical stuff such as Life Giver (+30 hit points) to oddly whimsical abilities. Mysterious Stranger, for example, occasionally summons a trenchcoated, .44 Magnum-armed dude who kills your target and disappears, spaghetti Western guitar riff resonating in his wake. Spend skill points and pick perks accordingly and it's easy to create anything from a plasma-rifle-slinging do-gooder to a computer-whiz cannibal.

Whatever path you take, peace and love have no place in the Fallout universe; a whole lot of mutants are gonna die. The Vault-Tec Assisted Targeting System (V.A.T.S.) -- pause time, target specific body parts -- is fun and works well despite the severed limbs and decapitations served up in horror-porn slow-mo (and that's without the aptly named Bloody Mess perk). And of course, assuming you don't sink all of your skill points into Science and Barter, you'll see real improvement in weapon accuracy and effectiveness as you level up.

You can only carry out so many actions at once in V.A.T.S., though, so some real-time combat in between V.A.T.S. attacks is inevitable. Here, Fallout 3 feels very much like Oblivion; it's less precise and polished than a dedicated first-person shooter such as Call of Duty 4. Distractingly bad character animations -- I'm talking man-on-the-moon jumps and running that looks suspiciously like ice skating -- and occasional camera problems, especially when you have an A.I. companion, make third-person view an option for Fallout series-nostalgia fetishists only (of which exist plenty).

Fallout's heavy emphasis on wholesale slaughter combined with a relatively small variety of enemies makes for combat that can get a wee bit predictable at times. The ubiquitous Super Mutants and Feral Ghouls both suffer from the same brand of chemo brain and love to charge into melee range. Until I picked up a plasma rifle and became a one-shot headshot machine, I'd start most indoor battles with some long-range plinking and then duck down a corridor, kicking in V.A.T.S. again for a point-blank shotgun blast or three at whatever bumbled around the corner. But then it does depend on who's holding the controller, too -- I watched other players around our office adopt a more Rambo-esque attitude, and while they lived and died from health pack to health pack, at least their finishing moves were more varied than my signature shotgun-to-the-face.