Mothership Zeta is the fifth and, so far, final piece of downloadable content for Fallout 3. As you might be able to guess from the title, this latest DLC has a rather unusual plot compared to the rest - while investigating a mysterious radio signal, you're suddenly surrounded by a blinding light and abducted by a giant alien spacecraft! In keeping with the retro-style humor found throughout the game, Mothership Zeta uses a lot of old stereotypes, including flying saucers, scrawny green aliens with big heads, crazy experiments on abducted humans, and a giant death ray.

While the appearance and feel of this DLC is quite different from anything else in Fallout 3, the gameplay is actually most similar to Operation Anchorage, with a pretty linear progression and a binary choice between stealth combat or run 'n' gun. In about the middle of the story, you'll reach a kind of hub and be able to explore different small sections of the ship in any order - three of them are required in order to knock out generators at the end of each path, while a couple of the others provide some unique weapons if you explore them - some of these paths have teleporters at the end that you can use to go back to the hub, a nice touch to skip some boring back-tracking. There are a few parts you'll come across that shake things up a bit - one in particular has the player up in a control room looking out over a hangar, activating several different energy emitters placed around the hangar to fend off a horde of charging aliens. The final battle is also unique, and while it's a bit confusing at first it's also a lot of fun and, in my opinion, the first true boss battle in the game.

Your companion will be left behind when you get abducted, but you'll have a few different companions to take with you through several parts of the ship. The first is a recently-captured Wastelander, with whom you'll find yourself sharing a cell until you break out together - she can also repair your equipment. Another is a medic abducted in the time of Operation Anchorage, who can increase the efficiency of the biogels you'll find lying around (the alien equivalent of stimpaks, though they can have some side effects on you) and eventually create Cryo Grenades and Cryo Mines, which freeze enemies but don't do much damage. The third is an Old West cowboy whose only real use is to help you out in one section of the ship and then die, so you can take his cool cowboy outfit for yourself. You will eventually get a Drone Control Device, which you can use to activate one of the enemy robots and turn it into your companion. You'll also come across a Japanese samurai that you have no way of communicating with (but you can also kill him for his cool outfit) and a little girl who likes to explore the ship by scurrying through its tiny crawlspaces, and helps you out by activating locked doors and such.

The main plot is pretty simple and straightforward, but you can dig around and find a lot of details that have been left by the developers. Scattered around the ship are a couple dozen clickable terminals that give you holotapes containing recorded interviews that the aliens conducted on their subjects. You can also talk with the characters mentioned previously and get a little more information on their back stories. Even with that, Mothership Zeta is still mostly an action-oriented adventure, but it's executed well so it's still fun.

The indoor environments are pretty cool looking, structured somewhat like the sewers and power plants of the Wasteland but updated to look more modern and techno-saturated - probably what people a few decades ago would've expected an alien spacecraft to look like. There are lots of fancy consoles everywhere, but you can't interact with most of them. Occasionally you'll come across a healing archway, which refills part of your health for free every few minutes - you can also modify it to refill all of your health immediately, but the archway will break after a few uses. Since I never used any of the archways more than once myself (having tons of stimpaks on hand, and the easy availability of healing biogels helps), I modified all of them for a free full heal.

The aliens themselves come in a couple of different varieties, with your standard soldier being rather easy to defeat, the worker who doesn't actually fight you, and the super-alien that has some kind of shimmering energy shield that makes him tough to kill. The ranged weapons that these aliens have on them are pretty fun to use, and functionally they're basically more powerful upgrades to the Plasma Pistol and Plasma Rifle. The rifle in particular has a cool effect when fired, that is best seen in VATS - it looks like firing a small black hole at the enemy. These weapons use a unique alien ammo however, and while there's plenty of it around the ship and on the aliens themselves (such that you'll end up with thousands of rounds); ultimately there is only a finite supply. You'll also be able to find several dozen rounds for the Alien Blaster, if you picked that up previously. The first weapon you'll come across, which you basically only use until you recover your equipment soon after you escape, is the Shock Baton, a melee weapon with a damage-over-time effect that is good for killing the early aliens you'll come across but not much use once you get the better equipment.

There are unique versions of the two main alien weapons that you can find - the Atomic Pulverizer is the blaster version, and gives you double the number of shots in VATS for about the same amount of damage per shot, while the Destabilizer is the rifle version and does more than double the damage of the normal alien rifle. There's also a unique Plasma Pistol called the MPLXNovaSurge, which fires double shots. It's the most powerful and enjoyable weapon I've come across in the game so far, fires a lot of shots in VATS, and turns enemies into piles of goo instead of piles of ash. Upon defeating the ship's captain you'll also get the Captain's Sidearm, a unique version of the Alien Blaster which fires triple shots that are each about a third as powerful as the blaster (so about the same damage). However, it uses the new ammo of which there are thousands of rounds on the ship, instead of the old blaster ammo which has a severely limited supply. There's also a unique shock baton called the Electro-Suppressor, but it doesn't seem to be much better than the regular version and I immediately placed it to one side.

There are a number of new items in Mothership Zeta, though you'll also come across parts of the ship that have stores of items from the Wasteland. An Alien Biogel acts much like a stimpak, though it can also impart a random side effect. An Alien Epoxy will repair your currently equipped weapon by about 15-30%, depending on your repair skill - a very useful item to have. You'll also find alien food of the squid or worm variety, and either small or large crystals which seem to be mainly used as currency (for caps back home). There's only one perk you can get - a 20% increase in damage done with alien weapons - if you find the shooting gallery area and kill everyone in it.

One of the few regrets I have is that I couldn't take the alien outfits, though I suppose they wouldn't actually fit on any human character anyway. You do end up with a full spacesuit needed for a short spacewalk, which doesn't have great stats, but it does look pretty cool. One of the cool design choices is that after you finish the story and beam back down to the Wasteland, you can still go back at any time to finish exploring or pick up equipment you had to leave behind that wouldn't fit in your inventory. The music is pretty standard, picking up tempo in battle and leaving you mostly to yourself while exploring. The voice-acting is great as usual, both in the holotapes you can pick up and the handful of NPC's you'll come across. On the technical side, Mothership Zeta is the first DLC in which I experienced zero crashes, and the game's launch went off smoothly on both platforms as well. There are still the few graphical glitches and such that have been present since the very beginning, and rare problems with the teleporters and quest triggers that will prevent your progress, though I never encountered any myself.

Depending on how much you explore, and whether you prefer a full frontal assault or a more stealthy approach, Mothership Zeta will last around three to six hours. It doesn't have the big, open areas and side quests of Point Lookout, or the added benefits of Broken Steel (such as the increased level cap and story extension), but this DLC is still a fun adventure that will net you some cool-looking and powerful energy weapons when you're done. Overall, Mothership Zeta takes the basic game design of Operation Anchorage and fixes many of its problems, giving the player a longer experience, with more interesting environments, enemies, and equipment, and several different and interesting small gameplay elements to break up the monotony. If you enjoyed the previous DLC, you'll probably enjoy this one as well, and the cheesy sci-fi themes will probably win over some new fans as well. One word of caution, however - if you don't already own Fallout 3, you may want to wait a couple more months for the Game of the Year Edition, which includes all five DLC for free.