Sure, it's heavily inspired by System Shock. But the original Dead Space is still a cracking action horror game that's worth your time, and it's free right now.
The game is free through Origin's "On The House" program, the same venture that resulted in games like Dungeon Keeper and Theme Hospital being free to download for a short period of time.
It's not specified how long Dead Space will be available for, but you don't need to download the game to keep it in your library. You just need to login to your Origin account (through the website or the PC app) and then redeem it into your library, after which point you'll be able to enjoy what some people say is one of the best horror games ever made.
Well, I don't know that it's quite that good. But the Ishimura makes for a great spin on a haunted house, as far as horror tropes go. And the game's free, so what are you waiting for?