Combat is the primary focus of the Fallout 3 DLC named "Operation: Anchorage". How much you enjoy the combat in the game will probably determine how much you like this content. Once you've paid your 800 Microsoft Clippy-bucks and return to the Wasteland you receive an emergency call from some members of the Outcast Brotherhood of Steel asking for backup. A new landmark is added on the southern end of the map, and you're on your way.
The Outcasts have discovered a hidden vault that they believe is full of precious pre-war technology. There is one catch: all this wonderful tech is locked behind an unbreakable door. The only way to access it is to successfully complete a pre-war virtual reality military simulation of the Liberation of Anchorage. It's a pivotal moment in the history of the Fallout universe where the United States successfully drives the Red Chinese out of Alaska. It's a great victory for the USA, but let's not mention that it contributed directly to the start of the nuclear war that followed. For reasons of plot, the only one who can access the simulation is you and your trusty Pipboy 3000. The Outcasts recruit you to help them out.
This Shakespearian simulation within a simulation looks nicely different from the bulk of Fallout 3. Society hasn't yet been destroyed by nuclear war, the sky is blue, the ground white with snow and ice. Like Oasis, it really feels like a refreshingly different place. There are four missions to complete, and each consists of getting to a particular destination and killing everything that stands in your way. You're aided by a squad of your choosing, either infantry, grenadier, sniper, missile launcher, or two brands of robot. They do help, by drawing fire if nothing else, and add some atmosphere to your character's more solitary existence outside in the Wasteland.
There are a few set pieces where you and several other heavily armed allies sweep through a large number of baddies. It moves quickly, and watching others in power armor while helicopters fly by and explosions shake the controller is fun. The one caveat here is that in all the excitement the thing crashed my Xbox. Just the one time, but it was a bummer, both in lost progress and in losing all the momentum of the action.
There's plenty of combat to be had in Operation: Anchorage, and if nothing else can greatly help you on your way to the "Doesn't Play Well With Others" achievement of killing three hundred people. It's a great way to rack up some XP. The top-notch loot gained at the end is a nice added bonus.