Back in the Saddle
After all but one person (the original marine) are massacred in Doom 3, Mars base is closed for a while. However, one should never underestimate both the curiosity and greed of man. The UAC, under the impression that a beefier group of marines would be a great failsafe, decide to reopen the mines from the original and find out what happened. Your new marine is apart of the excavation group, and as he touches a floating and glowing heart-like artifact, he opens another portal to hell from which an army of demons begin assaulting the base. If it makes you feel any better, if it wasn't your marine that touched the artifact, it would have been someone else and you'd just be dead, making for a poor game.
The box of the game boasts that there are 6 new demons to fight, which is partially true. 3 Of these new demons look like stronger and more magical hell-knights, and they act as 3 of the 4 bosses in the game. 1 of the new demons is just one of the original demons with a new skin (those floating head things now look like they are Egyptian, not organic). The 2 new demons that actually make a difference can be considered a revamping of the imp and hellknight, but they are different enough to be classified all their own. The new imp crawls on all fours, is significantly faster and shoots green plasma. The new hellknight has a television for a mouth, is extremely powerful and dishes out pain from his plasma cannon hands that can level you in seconds.
Given that these new monsters, as well as the originals, now spawn in groups of 4-6 instead of 2-3, you are going to need to rethink your old fighting methods. Luckily for you, you have a few new weapons at your disposal. The first is the new gravity gun like 'grabber', which can grab plasma balls and shoot them back at enemies. It feels faster and more deliberate than the gravity gun, which can either be a good thing or a bad thing depending on how sensitive your mouse is. The second new weapon is the Sarge's double barrel shotgun, which some will remember from Doom 2. The reload can be a pain in a tight spot, but few things withstand a pointblank blast from it, making it your new shotgun of choice. Finally there is the artifact you start with, which deteriorates your hand when you hold it (creepy). You upgrade it by killing a boss, and it's three modes are slow-mo, berserker, and invulnerability. It is smart to open doors before using this weapon, and you should always use it against the new hell knight, as it will save your life. The artifact feeds off human souls to work, so you need corpses aplenty to keep using it, but it is a godsend (no pun here folks) in battles.
D3RoE is what one expects from an expansion, with much more. In addition to the content you get a couple new toys that add some new game play elements. I only wish there were more genuinely original demons to kill in the expansion, as the new ones mostly feel like remakes of older ones. The extra content won't take long to get through, but it is worth sinking a few dollars into if you loved Doom 3.