"In terms of content, the co-op campaign is basically similar to the solo campaign, though there are additional enemies and power-ups to give two players their fills. And, in a decidedly caring touch, some of the dialogue is changed to reflect there being two marines trying to thwart evil, instead of just one. You'll notice a few other twists, such as doors that can only be opened when both players are present, and how a lot of the peripheral story stuff is stripped out to keep the game moving along. The gameplay is more fun in co-op than it is in solo (particularly if you toggle on friendly fire), even though it's functionally identical and easy as hell. Whenever you get killed, you just pop right back into the level and can run over to wherever you died and grab a backpack with all your weapons in it. Yet having a friend (or even a stranger) along for the ride will naturally make the journey more interesting, and having to pick off targets in narrow corridors while staying out of your buddy's way--and not mistaking him for a threat in all those dark shadows--adds a much-needed bit of depth to the action, not to mention an appreciable chunk of value to the entire package. Fans of the PC version might not be able to justify paying full price just to play Doom 3 again in co-op, but yes, it would be well worth their while to check this out."

"The first thing I noticed when entering the world DOOM 3 creates was the nearly seamless presentation. When the game starts, you'll find yourself walking through the halls, interacting with other employees and learning a bit about what went on before you landed on the planet. You're presented with a PDA at the beginning, and this will act as your information center as you play through the game, accessible by a quick press of the black button. There, the game's surprisingly deep story unfolds through a series of company emails, video footage, and audio recordings."