While your character remains nameless, you're no longer the same space marine who survived DOOM 3. This time, you play a combat engineer working under the command of Dr. Elizabeth McNeil, who worked alongside the nasty Dr. Betruger on Mars but was sent home as she began to suspect Betruger might be up to no good

One of the more interesting new monsters is the bruiser. Hell-knight sized, and just as big of a cause for alarm, these beasts will make you think twice before approaching a computer monitor. Why? Well, they’ve got one for a head and may lay in disguise as a computer console until you approach them.

...although Hooper points out that it's not quite the same, since your character still retains his normal movement speed. "You have complete freedom of movement -- you can dance around fireballs, or run up and peg creatures with a shotgun blast."

There's another new weapon that might raise a few eyebrows: the Ionized Plasma Levitator, also called the Grabber.
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It would be easy to treat the weapon as a knockoff of the gravity gun, but -- as was the case with Half-Life 2 -- the gadget was borne out of something the team had already been using during the creation of DOOM 3. "It's one of those things that's just fun, and we've had it around in our engine," Hooper explains, "we actually used it as a tool throughout development where we'd grab physics objects and place them around the world." While there was some thought to adding the gun to DOOM 3, the team decided against it. "We talked about that quite a few times, but we had such a big arsenal of weapons, and so many other cool things going on, that it was just one of those things that never made it in."