Focus on single-player
While Dead Space 2's multiplayer wasn't really a detriment to the game, it did lack creativity and felt a little uninspired.
Some fans have suggested co-op, or a horde-type survival mode against waves of necromorphs for multiple players, but we don't think it'll work.
As Resident Evil 5 proved, having another character with you at all times kills any feeling of isolation and loneliness. And look at Fear - the first one was a fantastic horror game, but the third and most recent entry in the series introduced co-op and ended up as shooter with some weird bits in it.
While that's not to say co-op horror can't work, we just think it won't be scary with another player there. You'd probably just be laughing with your mates while going through it, destroying the atmosphere in the process.
I mean, some form of multiplayer could work, but it would need a lot of special attention and care from the developers to make it anything worthwhile, but then that attention and care could be devoted to offering an amazing single-player instead.