Dead Space for the PS3/360/PC was a huge hit. It took a lot of people by surprise because they weren't really expecting much to come out EA and this game kind of snuck up on people. Due to it's massive success, a movie was made (animated) which wasn't too bad and some comics are floating around out there. To go on top of all this, a new Wii game is coming out soon called Dead Space: Extraction.
Dead Space: Extraction for the Wii is a rail shooter set in the Dead Space universe. Whether you've been following the storyline of Dead Space casually (you played the game) or religiously (played the game, got the movie, and read the comics, like myself) you'll appreciate this Wii game because it's a prequel. What do prequel video games do? They shed light on the story or the events leading up to the previous game you played. Dead Space: Extraction plans on doing just this as documented by this video from IGN.