The Resident Evil series has been building up to a resolution for a few games now, as it teased an eventual apocalyptic showdown with the games' central villain, the Umbrella Corporation.

In Resident Evil 4, they've had that showdown, and didn't invite any of us. In the first thirty seconds of the game, we're told that the American government shut Umbrella down and drove it out of business. The end was a whimper, rather than a bang.

That's your first clue. Capcom's made a few changes.

If there's a series in gaming that needed a shot in the arm more badly than Resident Evil, I'm sure I don't know what it is. After several games that were all variations upon a basic theme, RE was becoming incredibly stale. Each game was the same thing: a frantic scramble for ammunition within a monster-infested Victorian mansion. Yeah, the games looked good, as does RE4, but the gameplay was suffering.

Resident Evil 4 is the overhaul the series needed. Capcom's kept enough familiar elements that it's still identifiably RE, but thrown out much of the rest. The remainder's used as the groundwork for an all-out action game, by turns punishingly challenging and frighteningly visceral. It's hardly horror anymore; it's now chiefly concerned with shootouts and grossouts, but it compensates for the lack with plenty of exploding heads.

Six years ago, Leon Kennedy was one of the survivors of the destruction of Raccoon City, as seen in Resident Evil 2. Since then, he's joined the American government as a field agent, answerable only to the President. His new job is to protect the President's family, but the day before Leon starts work, the President's daughter Ashley is kidnapped.

Her trail leads to a rural village in eastern Europe, a place without roads or electricity. Leon goes there to ask a few questions, and discovers the village's psychotic inhabitants are all members of a murderous cult, and none of them are quite human anymore.

That's the first big change: no zombies. The cultists and villagers have certain undead qualities, yes, but they're actually intelligent. They use weapons, they work in teams, they'll try to flank you, and they'll try to dodge incoming gunfire. You really have to think tactically and move fast in order to win.

The second big change is how the controls work. Despite what some people might tell you, they're still much the same as in past REs; the difference is in perspective. Leon still moves like a tank, but this time, the camera's locked in position just behind Leon's right shoulder. It feels a bit like an FPS, and I really do wish that strafing was an option, but it works.

When you ready a weapon, you enter a free-look mode, allowing you to aim wherever you want with the help of a handy laser sight. So yes, you can go for headshots now. You can also disarm a target by shooting his weapon or his arm, stop a flying knife or axe by blasting it out of the air, kneecap someone to knock him over, or put a slug straight through their center of mass.

For the most part, you'll buy and upgrade weapons from mysterious Merchants, using coins and treasures you find throughout the game. The typical RE arsenal - 9mm pistol, pump shotgun, a Magnum - is present here, with the welcome additions of a scoped rifle, the mine launcher from Resident Evil 3, a submachinegun, and a one-shot rocket launcher.

This is a matter of some small concern, because unlike past games, Resident Evil 4 is all about the action. As a cohesive narrative, it has the general feel of a fever dream, with oddly-garbed monsters in human form attacking you with the weapons and trappings of feudal Europe. The average cultist will ignore discarded firearms in favor of a sturdy shield and a mace and chain. You have the edge on technology, but they usually outnumber you six to one and they're all insane.

At the same time, RE4 piles on the monsters. The villagers come in a wide variety, from crossbow-wielding snipers to madmen with belt-fed machine guns, but you'll also come up against a freak legion of hideous mutants who have to be seen to be believed. Some are constantly regenerating experimental bioweapons that're nearly invincible unless you exploit their Achilles' heel; others spring forth from the bodies of dead cultists, like a lethal Jack-in-the-box.

RE4's a long, running battle, with the occasional puzzle to break up the action or complicate a fight. For the most part, this is Resident Evil as an action movie, with Leon recast as a highly trained soldier who's more than equal to the task at hand. Ammo conservation is a thing of the past, for the most part; there are plenty of bullets for the taking, and plenty of dead enemies will drop more. Your weapons are there to be used, rather than hoarded against some oncoming catastrophe.

While they were reinventing the game, they also reinvented the way RE4 approaches a fight scene. At one point, you'll battle a small army of mercenaries from the back of a moving truck; at another, Leon has to take out dozens of armed opponents while riding in an out-of-control mine car; in yet a third instance, you'll have to go spearfishing for what appears to be a carnivorous demon mutant whale from the back of a rickety rowboat. In between, there are plenty of opportunities for straight-up gun battles in a wide variety of locales, from the dungeons and halls of an ancient castle to the dugouts and bulwarks of a military checkpoint.

There are fights in RE4 that'll still be spoken of years from now, which'll influence game design for years to come. RE4 lasts about twenty hours, when all's said and done, and you'll spend most of that time high on adrenaline, holding onto life by the skin of your teeth.

The last facet of the reinvented gameplay's the one part of the new formula that annoys me: Quick Time Events. You've seen similar mechanics in Dragon's Lair or Shenmue. At certain points during the game, to avoid a boss's attack or do something cool during a cinematic, you'll have to hit a couple of buttons with split-second timing. For much of the game, this isn't a problem, but the timing gets increasingly tricky as you reach RE4's second disc. There's one important sequence that's just five or six QTEs in rapid succession, each one of which is easy to mess up. It's unnecessarily frustrating, particularly given the tough-but-fair attitude that pervades the rest of the game.

I can think of a lot of other things I'd like to see in Resident Evil 4, but you've got to look at what's actually there. Capcom's reinvented the wheel in high style, and while they've traded in their usual attempts at horror in favor of intensely creepy action, the game's better for it. This is the first great GameCube title of 2005.