Dead Space never felt like it was lacking a multiplayer mode. Isaac's lonely, stomping travels aboard the USG Ishimura were perfectly suited to a solo experience. Even a co-op mode would have felt jarring - the game's strongest asset was its doom-laden atmosphere of desolation, and replacing that with the simple intensity of Resi 5 would have been completely off-brand.
So the first thought when you hear of Dead Space 2's four-player co-op mode is: "how will that work?" The second is: "hang on, four players facing an onslaught of mutated corpses? That's Left 4 Dead, isn't it?" And the third, and hopefully final, thought is: "perhaps I should just stop sitting here thinking, and just read the rest of this article that someone went to the trouble of writing".
Visceral Games has wisely chosen against the poor fit of a deathmatch mode. Instead, four Isaac-alike engineers will choose from five maps with a specific objective to pursue. Objectives that'll be hindered by a constant assault from player-controlled necromorphs.
So yes, it is a bit like L4D - you're not fighting to win, but to survive - however, a lot of effort has gone into preserving Dead Space's tone.
The Titan Mines map sees you assembling and detonating a bomb, and blasting your way out of the area. The Escape map has you priming and using the Escape pods. As an engineer, you'll have Isaac's stasis abilities, and there's still a focus on tactical dismemberment to fend off the 'morphs.
Unlike the humans, there's a choice of necromorph breeds. You can play as the Lurker - a wall-climbing mutant that means engineers will have to be aware of all the hiding places. The Lurker can lob missiles from any angle, making him well suited to players with a strong sense of direction - people who'd be comfortable in one of MC Escher's impossible reality drawings.
Meanwhile, The Pack is most like Left 4 Dead's Hunter - pouncing and pinning his quarry. Instead of requiring a team-mate to help you up, though, you can fight him off yourself if you are able to mash buttons faster than your posthumous opponent. The Spitter is the long-range acid-hocker who is able to charge his attack - the necromorph equivalent of a hacking up some phlegm. There is another class, The Puker, but he's still under wraps at the moment. The clue's in the name, though.
An unexpected and unnecessary bonus (we're already sold on Dead Space 2), the multiplayer is tense, entertaining and in keeping with the Dead Space feel. It's an excellent bolt from the blue.