The original Dead Space video game is currently completely free for download on Origin.
This deal will be available for a limited time, according to Origin, as these specials can "appear or disappear at any time." The On the House program gives away PC games, expansions and downloads for free. Once downloaded, these games and DLC are permanently available, meaning you don't have to pay for a service to keep them (like PlayStation Plus).
Originally when this deal was noted, many thought it was a glitch or even an error on the EA Store. Turns out Dead Space is the first game to be offered under this new On The House service.