Set roughly six months after the original Gears of War, Gears of War 2 occurs during the aftermath of the human forces' successful detonation of the Lightmass Bomb in the depths of the Locust tunnel system at the end of the first game. This weapon of mass destruction obliterated most of the Locust Horde's forces but simultaneously caused the massive vaporization of Imulsion, an incredibly valuable low-viscosity liquid fuel source found within the depths of the planet. This enormous amount of vaporized Imulsion escaping into the atmosphere caused a never before seen and ultimately fatal disease among the remaining human population referred to as "Rust Lung." Additionally, the remaining Locust forces have brought a new weapon to the battlefield, one that can create massive sinkholes in the crust of the planet large enough to encompass entire cities. The last human stronghold on the planet, Jacinto Plateau, which until now was impervious to such attacks, is threatened by this new weapon. Once again it's up to Marcus Fenix and Delta Squad to save humanity before Jacinto Plateau falls to the Locust. Much like its predecessor, Gears of War 2 is a third-person shooter, making use of an over-the-shoulder point of view for the majority of its gameplay. The game will still maintain a large amount of emphasis on using cover (which is now destructible), and will feature improved close combat gameplay, such as the ability to have button-mashing chainsaw duels with computer-controlled enemies or human opponents online. Additionally, Marcus can now make use of defeated enemy Locust as human-shields, can crawl to safety when seriously injured, and can perform more finishing moves on fallen enemies. Though portions of the game will retain the same sort small battlefields seen in the original game, it's also now capable of presenting areas that are much larger in size and scope (thanks to the Unreal III engine). Epic is also making a significant attempt to enhance the storytelling of the game with character back stories, letters and journals that can be discovered while playing, improved dialogue, and perhaps even a love interest for the main character. Gears of War 2 will also feature parental controls, changing the blood in the game to sparks and removing the swearing. Without these options, blood and gore have been increased from the first. Wherever your character moves, a trail of blood will follow them depending on how injured they are. The same goes for human meat shields and downed/crawling characters.
Plot *SPOILERS*
In Gears 2, the Locust have gained in strength. Though the humans thought that the Lightmass Bomb would end the war, destroying the Locust where they lived, all it did was wipe out the Kryll breeding grounds, making travel at night somewhat safer.The singleplayer campaign starts out with Marcus Fenix and Dominic Santiago of Delta Squad being joined by a new member, Benjamin Carmine. Carmine is the brother of Anthony Carmine, who was a soldier that died in the first act of Gears 1 at the hands of an unseen sniper, a fact that Dom makes direct reference to more than once. Marcus and Dom train the rook, which also serves as a training sequence for the player. Afterwards, they have to defend the hospital they are at from a Locust attack. Along their way through the hospital, they meet up with Tai. Tai has earned the nickname "Bulletproof," and he has a very spiritual approach to battle. They manage to clear out the hospital, and are then informed that they must take part in a counteroffensive againt the Locust. First, it is made clear that Dom is looking for his wife, Maria first and foremost. Anya, the intel supervisor, informs him that she might have found a trace on Maria, but it's unlikely she's still alive. Dom demands to know the intel, and Anya informs him that his wife may have joined with the Stranded, humans that are without support in the heart of Locust territory. After that, the crew meets up with Dizzy, a stranded that has joined the Coalition of Organized Governments, or COG. Dizzy will ride a Derrick, a tank of sorts that transports COGs, which he has nicknamed Betty and has become rather affectionate toward. Along the way, they take on Reavers and Brumaks, both beasts of burden used by the Locust as air travel and tanks respectively. They eventually arrive in the town of Landown in an attempt to retake the town. Many troops fall in the assault, but eventually they manage to clear the town. A victory for the COG! They go down into an Emergence Hole in pods that dig through the surface, but not before seeing a Locust General they haven't seen before wreak havoc amongst their ranks. Markus and Dom are already strapped into pods when this agile Locust cuts through two tanks with a twin-bladed chainsaw and advances toward them. The General is distracted by Tai and Dizzy, but Markus and Dom are unable to provide help though, as the pod was already locked and programmed. Deep underneath the surface, they end up the Locust lair, known as the Hollow, where they witness a humonguous worm digging around. They quickly realize this giant worm is what is causing entire cities to sink. Eventually ambushed and outgunned, they two COGs are saved by Private Augustus Cole, still every bit as exhuberant as before. They continue along, to find another friend from their previous campaign, Baird, the demolitions and intelligence expert. They free him from the pod that he was locked in, and he tells them the Locust were intending to "process" him, though even he isn't sure what that means. They soon find out though, as they board a Locust Torture Barge.

Pvt Augustus Cole

The Barge is a zeppelin-lookalike where the Locust torture humans. Marcus finds Tai in one of the cells, though the mighty warrior seems to not quite himself. Marcus hands him a shotgun to help fend off locust that are converging on their position. Tai regards the gun, still not speaking, and turns the gun on himself. Marcus is horrifed and recovers Tai's COG tags, with Baird commenting that the Locust had completely broken him.They try to leave the hole by helicopter, but the giant worm that had seemingly been stalking them eats them before they can get away. Carmine falls in the beast's mouth before it swallows the chopper. Since the beast swallowed them whole, the other COGs remain together and in one piece inside the worm. They decide to take it out and look for Carmine. Avoiding stomach acid, digestive teeth and the creatures larger-than-usual white blood cells, they find Carmine fending a swarm of the creatures. Though the creatures are scared off, it's too late for Carmine, who has already been torn apart by them. Carmine says his final words to Marcus: "Sarge?..(Marcus replies "Carmine..." sadly) I hurt sarge...tell my brothers... tell my ma... tell em i love em, and...and.." and dies. Marcus Fenix collected his COG tag, number 838186-22AO3-SF and a letter that he had wrote to his older brother Clay, to deliver both to Carmines family.After Carmine's death, Fenix and crew make their way to various hearts, severing their aorta's as they go with what is colloquially known as a chainsaw bypass. They eventually kill it and cut their way out.

Dom, as he vows to take down every single one of the Locust

After that, Fenix orders a Raven to pick them. However, instead of a pickup the Raven drops a tank, the Centaur, to the embattled COGs. Colonel Hoffman explains to Delta Squad that they have a new mission: They must investigate an abandoned outpost recently discovered by the COGs. Though Marcus feels that they've done enough, killing the giant worm, Hoffman insists and so the COGs board the tank. They arrive at the outpost in terrible weather. Marcus orders Cole and Baird to guard the Centaur, while he and Dom go inside to investigate. They find a large security door, and an AI that tells them they need proper identification to enter. Marcus doesn't play around and simply orders Baird to build a large bomb to blow the door open. They fight off some stray wretches, before carrying the bomb back to the door and blowing it open. Marcus and Dom head deeper into the facility to make a shocking discovery: Locust-like creatures in glass tubes, apparently mutated from humans. It gets even more unpleasant as those things, dubbed "sires," decide to wake up. Marcus and Dom fight their way out, chainsaws proving effective against the abominations, only to find the bad weather has turned into razor hail, a deadly hail made of ice shards. Staying under roofs at all times, they manage to fight their way back to the Centaur, where Baird needs some protecting, for the weather has damaged the tank. After fighting off a small swarm of Reavers, Baird announces, after much complaining, that he's fixed the Centaur. Delta takes off, leaving the lab behind for the mountain outpost where the Locust are based from.