A friend of mine happened to mention how much he enjoyed Dead Space 2, and although I had skipped the first installment, I decided to take a look at the franchise's new game. There's a lot to like here, and an interesting mix of old and new elements borrowed from a lot of different games, and a lot of different sources.
Warning: spoilers ahead! This is not intended as a "find out enough to see if you want to buy it" sort of article, but a detailed look at a lot of parts of the game's story and design, and it WILL spoil the ending for you if you haven't played the game.
Derivative Space
This may be an unfair criticism, since one of my favorite franchises, Halo, draws heavily on concepts from other works: Aliens, Ringworld, Iain M. Banks' Culture novels, and several others. A broad-stroke summary of Dead Space's story would end up reading a lot like a mismash of ideas from other films. A strange, inscrutable artifact is found that holds vast and terrible power-- much like the Monolith in 2001, like the Halo array in the Halo series, and like the Beacon in Mass Effect. The artifact, which is called the Marker, sends out a signal that makes ordinary people go insane, and makes "smart" people see symbols, at least one of the side effects of which seems to be imparting the knowledge and abilities necessary to build Markers, as well as a drive to take the steps necessary to use the Marker to achieve Convergence, which appears to be a unification of all humanity into a single being, much like Instrumentality in the Evangelion universe. The Marker is revered as a holy artifact by a religion called Unitology, a thinly-veiled doppleganger for Scientology, and they are one of the groups struggling for control over the Marker and those exposed to its signal. They seem to be actively working towards Convergence, while others attempting to exert influence over the Marker and those exposed to it-- namely Earth's government-- seem to be working towards something else.
The supposed immense power of the Marker explains why our protagonist, Isaac "I See What You Did There" Clarke is so important. In the first game, the mining ship Ishimura, with Clarke's significant other on board, found a Marker on a planet called Aegis VII. The Marker's signal caused people to transform into Necromorphs-- hideously distorted, murderously violent zombies with a wide variety of super powers and biological attacks. In other words, space zombies. There are a lot of similarities between Dead Space and Left 4 Dead in their pantheon of opponents: large, powerful creatures with devestating melee attacks, creatures that attack from range with fluids, little creatures that hop on your back until you throw them off. The Marker, I guess, is Dead Space's version of the AI Director, choosing what combinations of necromorphs to send after the player.