Gears of War

another epic favorite of mine, and it fits because the game was actually made by the Epic Games Studio.

Gears of War is about humanities strruggle for survival against the sub-terrainian alien horde know as the Locust. Go figure, humanity is losing.....badly.

the Locust have begun to cause cities to sink below Seras (name of the planet) surface and are otherwise destroyed. The last haven for humanity is the city of Jacinto which is a city that was coincidentally built on a thick layer of bedrock that the Locust can't dig through. unfortunatly that doesn't stop them from marching on the city from the surface, which they do and they are actually winning, albeit very slowly.

the Humans begin to mount a counter strike where they will dig down to the Locust Hollow and hit them from within. the plan takes place in the already overrun town of Landown. things go off without a hitch even with Locust resistanc and the COGs begin entering the empty Locust controlled Hollow.

once in the Hollow the COGs find out about a plan by the Locust to use a giant worm whom they beleive to be a god. the worm being several time the size of a 747 jet airplane begins singing small cities around Jacinto in hopes that is will cause the city of Jacinto to sink as well.

the Player eventually finds that the Locust are actually fighting a civil war as well as the war with the humans. The Locust hope to sink Jacinto in order to kill off the Lambent so they don't contaminate the planets surface.

Once you find all of this out you are then thrown in a battle for control of the Locust Queens palace. Both the Locust loyalists and the rebel Locust Lambent are fighting for it as well, the loyalist to defend the queen, the Lambent to kill the queen, and your team who are also trying to kill the queen.

once in the queens throne room she divulges her plan on sinking Jacinto and you come up with a plan to sink it beforehand not only killing the Lambent, but the rest of the Locust horde as well. the plan succeeds by causing a Lambent Brumak to explode.

all of that is all of what I know rght up until the end of Gear of War 2, I can't wait for GoW3