Dead Space and Dead Space 2 are on sale, the pack is $12.49 USD.
I bought them in the last sale. DS2 has DRM, although I've only run Dead Space 1 - and I thought the interface was so horrible that I stopped playing and eventually uninstalled it. I would not recommend it.
I couldn't figure out how to navigate a menu that came up, because none of the obvious keys did one of the functions and the keys for menu stuff were not mentioned in the key assignments; there were arrows on the menu for switching tabs or something, but I couldn't find the keys to activate them, and there was no way to use the mouse with the menus as far as I could tell, as they were 3d in the game and you couldn't get a cursor to click on them ever as far as I could tell. It was irritating as hell. A mouse would have been 5000% more effective clicking shit than trying to use the keyboard or whatever, but it was impossible because they chose to make fancy in-game 3d projected menus and not use any kind of click detection. I felt like throwing the game out a window, but it was FRAKKING DIGITAL. DAMNIT STEAM! I had to settle for uninstalling it.
(Also it was considerably more difficult than I expected to hit enemies in their limbs using a mouse, almost like they did something wonky with the mouse aiming code.)