The story of the original game was largely forgettable, but it did a fine job of establishing the world, the characters, and the conflict. Gears 2 assumes you're already up to speed on this stuff and throws you back into the role of Marcus Fenix. Now the leader of Delta Squad, Fenix and his ever-present hetero life-partner, Dom, are the men on the ground doing the heavy lifting in the humans' battle against the Locust. Those guys, in case you forgot, are the mysterious mixed-species group of underground-dwelling enemies from the last game.

Gears 2 opens with a brief, optional training sequence to get you back up to speed on topics such as hiding behind things and shooting stuff. It seems that the Locust attacks have grown more bold in recent times, and they quickly attack the hospital being used as a base of operations for the human forces. This erupts into a full-scale operation that sends Fenix and his team below ground once again, to take the fight directly to the foes. It seems that the Locust have been sinking more and more cities, and the last human stronghold at Jacinto is in danger of falling, as well. That would probably be a bad thing.

Immediately after the training sequence, Gears of War 2 gets down to business and lets you know that it's not messing around. The game works on a much larger scale than its predecessor, and an early vehicle sequence has you riding on a rig through waves of Locust troops and, as luck would have it, a handful of creatures that served as bosses in the first game. These bosses get absolutely ripped to shreds by the human forces. Big, imposing foes like the Corpser or the Brumak are practically treated as jokes right out of the gate, with more than one Brumak getting ripped apart by the turrets on your rig. This ends up feeling pretty awesome, as it lets you know in the game's early moments that you should expect to see bigger, more deadly stuff over the course of the game. And the rest of the game delivers on that unspoken promise.

As you move through the story, some of the things left open from the first game are filled in a bit, and you get to see a bit more of what's going on underground in Gears 2, but overall, I feel like the campaign asks more questions than it answers. For every glimpse of the Locust hierarchy you get, you seem to get two glimpses at things that are touched on, but not explicitly explained. While there's a lot to infer about things that occur during the campaign, some things feel too open. Either way, the game certainly leaves enough openings for a meaningful sequel, but not so many that you're left feeling unfulfilled at its conclusion. And it's probably a testament to the game's world that I'm left wanting to know more, instead of just slapping the "mindless shooter" tag on it and moving on.

Gears of War 2 has new weapons and a new maneuver or two. Nothing that totally redefines the experience, as far as the mechanics go, but enough to keep things moving. The structure of the campaign is good about giving you variety. This isn't just moving from grub hole to grub hole, slinging grenades all the while. New enemies such as the ticker, which is sort of a skittering land mine that will run up to you while you're behind cover and explode, force you to be on your toes during fights. Enemies wielding flamethrowers or large shields also require you to vary your tactics a bit. In addition to that, there are a few vehicle sequences, each of which is really well done. They successfully break up the action at just the right moment and are pretty intense, too.

The new weapons include a new class of heavy weapons that you can lug around at the expense of your speed, much like Halo 3's busted-off turrets. Most of these weapons are found in specific locations, though, so you won't really find yourself lugging around a mortar cannon from one fight to the next. The mortar's quite fun, letting you rain down with deadly missiles on your enemies, provided you can figure out the right distance to fire them. There's also a big chaingun-style weapon that's carried the same way. Smaller, but still plenty effective is the flamethrower, which quickly burns up your enemies. There's also a new burst-fire pistol that lays out a few rounds each time you pull the trigger. That said, I found myself sticking with the sniper rifle and the lancer (that's the main assault rifle that comes with a chainsaw bayonet) almost exclusively.

The game's new moves include a chainsaw duel and the ability to take hostages as shields. When lancer blades clash, a button-mashing icon appears and a chainsaw duel starts. The person who slams B the hardest will win and cut the other person apart. Pressing A when near a downed enemy will pick him up and use his body as a shield. You're slowed down and forced to use a pistol when doing this, but you also become effectively invincible against most incoming fire. Once your "meatshield" takes enough damage, he'll blast apart into chunks or fall to the ground, leaving you exposed. You'll also find proper shields, which you can hide behind while on the move or plant in the ground and use as standard cover.

Like the previous game, you can play through the campaign cooperatively, which is especially useful for the game's hardest difficulty setting, which only unlocks after beating the game once. There are four difficulties in all, with the second-highest, hardcore, feeling most like the first game's default level of difficulty. Below that, the enemies get easier and easier to deal with. The new casual difficulty feels like it's designed for people who don't play many games, and it has the side-benefit of letting you get revived by your AI teammates when you get shot and go down. It's a wider range of difficulty than most games have, which should ensure that there's a setting for just about anyone that picks up a controller. When playing cooperatively, each player can choose a different difficulty setting, which adjusts the damage done and the damage taken by the player.

There's another new cooperative mode called Horde. This mode puts up to five players on one of the game's multiplayer maps. Then the map is repeatedly infested by AI-controlled enemies. They come in waves, and there are 50 waves in all. The waves move in cycles of 10, so wave 10 has the most and nastiest variety of enemies. Then it resets, so wave 11 goes back to fewer enemies, but one of the enemy's statistics--accuracy, health, or damage--is increased. Even on the game's lowest difficulty setting, this mode gets really tough. It's a great way for players who aren't comfortable with the thick, macho level of competition happening in the rest of the online modes to still enjoy the multiplayer maps. It's a great addition.

Of course, you can also use those multiplayer maps for team-based multiplayer. The player limit has been raised to 10, making for a collection of five-on-five modes. The old favorites, such as Warzone, Execution, and Annex are still here and totally intact. The Assassination mode from the first game has been tweaked and renamed Guardian. In Guardian, as long as the team's leader is still alive, the other players can respawn. So a team must hit the opposing leader to stop the respawns, then finish off the remaining stragglers to win a round. Wingman breaks players up into teams of two, and the last team standing wins the round. It's a good inclusion that really emphasizes teamwork and sticking together. There's also a new capture-the-flag-style mode called Submission, which has you fighting over a stranded human and attempting to drag him off to the capture point. So there's a lot to do when you're playing multiplayer.

Not only is there a lot to do online, but it's all quite good. Gears of War's multiplayer turned out to be vastly popular, and the things that made it stand out are here in the sequel, and often improved upon. The game makes use of a good, solid party system that makes it easy to group up with friends. Bots are also available if you don't feel like taking on the masses. And the map design is great. There are ten such maps already on the disc, and the game comes with a download code that lets you download five more maps. This "Flashback" pack gives you five of the maps from the first game, and they've all been given a graphical makeover to bring them up to par with the better graphics of the sequel.

Yes, the graphics in Gears of War 2 are quite a bit better than the original. But you might not notice that unless you directly compare the two games. For me, nostalgia had already kicked in for the first game, and the first few times I played Gears 2, it looked as impressive as the first one did in its day. It's only upon direct comparison that I noticed how much more detail the world contained, from the ugly scar on Marcus' face to elaborate underground palaces. It's breathtaking, in spots. Also, it's quite colorful. This isn't "just another brown shooter." Even when you're underground, you'll see bright, colorful areas that really catch the eye, and lighting that really makes things stand out. You'll also see all that at a more stable frame rate than you did last time out. Things like cutscenes run more evenly, too.

About the only negative thing I could say about the visuals is that you'll often see rough textures on-screen when a scene first loads, and then the real textures fade into view after they're loaded. It's minimal, but noticeable. Also, the load times are reasonable throughout. I tested the game out both on regular "old" Xbox 360s along with the currently available preview version of the new dashboard that will be released on November 19. The game loads fine off of the disc, but you'll see a bit of a speed increase on your loads if you fully install the game to a hard drive.

The game's audio maintains the same sort of dread-inducing music as the original game, with a few little hits and stabs thrown in to call out dramatic moments, signify the end of combat, and so on. The game's audio is another high-point, with lots of squishy, meaty noises that accompany when you blast someone apart with a shotgun, cut them up with a chainsaw, and so on. There's more battle chatter in Gears 2, and you'll hear friends and foes alike call out specific enemy locations, such as "behind the car!" It makes the battlefield feel a bit more alive.

The characters from the first game return with their voices intact. The four-man crew from the first game are joined by some new blood who fit right in, but really, the original foursome are still the stars of the show. Marcus sounds even more grizzled, gravelly, and pissed off this time around. Dom, who is now pretty obsessed with trying to find his missing wife, alternates between anguish and anger. Baird continues to be a sarcastic jerk that you'd like to slap around a bit. And then there's Cole. The Cole Train's on-screen entrance in Gears of War 2 is probably one of my favorite moments in the entire game.

The differences and enhancements in Gears of War 2 feel very calculated and intelligent. It's clear that no one set out to break things that worked before, and the most dramatic steps were taken in an effort to widen the game's appeal to players who might not be good enough to play it, otherwise. But it takes on this task without dumbing itself down and alienating the people who already liked the first game. Academically, it's interesting to see this balancing act in motion. But all you really need to know is that Gears of War 2 is a terrific, kick-ass shooter with enough stuff in it to keep you busy for a pretty long time.