Gears of War is perhaps best known as a co-op game. Sure, it has competitive multiplayer, and sure, it has a single-player component, but neither embodies the fun of Gears of War: hopping into a game with a friend and blowing the crap out of monster hordes. This applies to the game's main story and the extra multiplayer modes, such as the ever-popular Horde mode. Epic Games realized this and decided that, for Gears of War 3, co-op should clearly be the focus. It's not a multiplayer-only game by any means, but everything we saw from the game made it clear that playing Marcus solo is going to be a much greater challenge than working with a team.

Gears of War 3 is set eight months after the fall of Jericho. Humanity is in terrible shape and barely hanging on to what little land it has left. When we join protagonist Marcus Fenix, he and the other Gears are living on an aircraft carrier and simply trying to make it through the day. All surviving humans are now soldiers, men and women alike, and it's looking like the last days of humanity. As if that weren't bad enough, the Locust have begun to mutate into a strange new form called the Lambent. In short, things are not looking good for any humans left on the planet.

The Gears of War 3 demo opens up with Marcus and the rest of Delta Squad on their way to a nearby human stronghold. The Locust are out in full force and doing everything to stop the humans from reaching the safety of the base, where Marcus' friends are attempting to reboot an old Hammer of Dawn weapon. The game starts shortly after a truck crash forces the humans to leg it the rest of the way to the base, surrounded by Locust hordes. On the surface, the gameplay looks similar to the older Gears of Wars titles. You and your three teammates are forced to fight your way through the Locust swarms using only your wits, skills and some of the most brutal weapons ever devised. One such weapon, an earlier version of the iconic Lancer rifle, has replaced the chainsaw bayonet with a simpler, but no less brutal, classic style bayonet. Marcus uses this to great effect to brutalize the enemies in his path, and it's clear that the killer animations are as violent and over-the-top as ever.

Most of the other moves are back as well. You can grab enemies and use them as shields, and you can slam a grenade into their back and kick them at foes as a makeshift weapon. It's effective and brutal at the same time, and it's a great way to turn enemies against one another. There's also a greater focus on making you work with your team, such as the ability to switch guns with an ally and change who is taking which combat role. It's a good way to avoid the usual problem of "the guy with the sniper rifle is stuck in close quarters" that co-op games tend to have. It's a nice way to make it feel more like you're a team, instead of four people who happen to be standing near one another.

The Locust are not the only enemies you'll have to worry about this time. After defeating a group of attackers, Marcus and friends are interrupted by a giant tendril that burst forth from the ground. This was our first encounter with the Lambent, which are terribly mutated members of the Locust horde that are filled with a glowing deadly emulsion. The first enemy we saw was a mutant drudge; it started off pretty normal but promptly began growing tentacles and spewing emulsion everywhere. If you don't kill it fast enough, it might explode, and if you leave parts of it intact, you risk it crawling off and becoming a new danger. They require significantly more firepower than their Locust counterparts to take down, and they also seem to dish out more damage. On the plus side, there's a benefit to killing them with melee attacks. In one instance, Marcus kicked a Lambent toward the enemy, where its explosive death was turned in the player's favor.

Things turned sour again with the appearance of a Lambent Berserker, which, as Gears of War fans will remember, are the biggest and baddest Locust in the neighborhood. Nearly invincible and supremely powerful, they were one of the biggest threats you faced in the previous games. The Lambent Berserker makes the regular model look almost friendly. It's fast, large and violent, with the ability to jump into the air and come crashing down on targets, or charge at them and tear them apart. Marcus and pals are helpless in the face of the Berserker and are forced to make a run for safety. At the same time, the Hammer of Dawn finally comes online and begins to target the enemy. Marcus and friends make it inside, just before the deadly beams of satellite energy blast the Lambent Berserker. All is quiet for a moment, before the gate of the fortress begins to buckle and twist. Then, seemingly unharmed, the Berserker leaps over the gate and down toward the assembled crew. That is where our demo ended.

That isn't where we stopped getting new info about the game, as a few more interesting tidbits are revealed. Gears of War 3 will introduce the Silverback personal armored exoskeleton, which is basically a suit of robot armor. A character can hop into the Silverback and become a walking weapon of death. The suit houses a built-in machine gun and rocket launcher, and it's heavily armored enough to sustain serious damage and keep going. It's also agile enough that you can perform some classic Gears moves in it, such as curbstomping an enemy with the mech's giant metal feet. It also has the ability to transform from Assault mode into Stationary mode. As expected, you can't walk in Stationary mode, but the mech forms a makeshift cover for whatever is behind it, allowing you to be a walking wall for the rest of your team. You can even form cover and then hop out to use it yourself. We didn't get to see the Silverback in action, except for a brief glimpse at the end of the demo, but it sounds like it should be a very interesting weapon in the hands of a skilled team that works together.

The most exciting demo was of the new Beast mode, which is a multiplayer mode that's based on the idea of Horde mode in Gears of War 2 but places you on the other side. Players take control of the Locust and are sent to attack a human stronghold. The goal is to destroy the enemy stronghold as fast as you can, but it isn't quite as easy as picking a Berserker and going to town on the poor humans. Most of the Locust types are locked at the start of the game, so only the weakest, like the Wretch, are available. You earn tokens by killing enemies or destroying parts of their base, and you can spend the tokens to unlock other playable Locust forms, slowly building up to the big momma Berserker herself. This is a five-player co-op mode, one more than the main story, and it looks like a blast. There's a strong encouragement in this mode to work together. A suicidal self-detonating Locust is very cheap and very powerful, but it's also very easy to kill on its own. If players work together to distract the enemy while the sneaky suicide bomber makes its way into an enemy crowd, you can devastate the human defenders far more effectively.

Gears of War 3 is a co-op game. It may technically have a single-player component, but everything we've seen makes it clear that co-op is the way to go. Whether it's the larger cast of characters, the deadlier enemies, or the new weapons and items that encourage cooperative gameplay, Gears is about beating down the Locust hordes with your pals at your side. Co-op is an appealing part of any game, but it rarely receives the same focus as the single-player or competitive aspects. With Gears of War 3, Epic Games makes it very clear that it knows exactly why people like the Gears franchise.