Mothership Zeta marks the end of Fallout 3's monstrous life. Really. Bethesda has said there will be no more add-ons to this quite stupendous, enduring game. It's sad, really. Sniff.

It seems appropriate to ask whether Mothership Zeta, the fifth and final Fallout 3 add-on, is a worthy finale. It seems appropriate to ask how Mothership Zeta compares to the add-ons that have proceeded it. It seems appropriate to ask whether I'm going to get any kick ass new armour and weapons I can use to lay waste to the, er, Wasteland. Unfortunately, the answers to these questions aren't going to please those hoping for a Point Lookout-quality addition.

Mothership Zeta, if you don't already know, is set on an alien space ship, the kind you'd expect to see in a sci-fi comic book from the fifties. That's fine - however outlandish the premise, or even the existence of aliens at all, Fallout's got form. One) there was a crashed UFO and an alien blaster in the original Fallout. Two) Fallout's universe is a retro-futuristic Americana vision of the future. It's what people from that era reckoned it'd be like in the 21st century. Flying cars, plasma weapons and ALIENS! Roswell and all that jazz - alien abductions, alien blasters, little green bastards with anal probes who were probably in league with the commies. If, as a die-hard Fallout purist, you're rubbed the wrong way by the very mention of aliens, then you'll probably hate this DLC, because it's fit to bursting with them.

It begins with a broadcast. The signal is a ruse - you're abducted, whisked off into outer space (sans Dogmeat, Fawkes or anyone else you might have accompanying you). You wake in a holding cell, stripped, predictably, of all your weapons and armour. There you meet a tough talking female wastelander called Somah. Before you've had a chance to check your crown jewels, you see a mechanical claw pluck a man from a nearby cell and carry him off kicking and screaming into some godforsaken pit of experimental doom. Clearly, these aliens aren't here for tea and scones.

The emphasis is on killing aliens. Lots of aliens.

And so it's escape time. We won't spoil it for you, but we will say it's not hard to get out of your holding cell. And from the moment you pick up your first alien weapon, Mothership Zeta quickly descends into the very experience we feared.

Fallout 3 is an awful shooter. It simply doesn't work played as a typical first (or third, but we can't imagine anyone plays the game in the poor third-person view) person shoot em up. But that's okay, because when combat is required, the brilliant VATs system does a great job of making the rampant destruction of your enemies fun and very, very bloody. And then, usually, there's some NPC interaction and beard-scratching decision-making for pacing. Mothership Zeta disappoints because it basically asks you to kill hundreds of aliens and other enemies we won't spoil in samey corridors and rooms for five hours without any role-playing to mix things up. There are so many aliens and guard drones to kill, usually at the same time, that it's impossible to use VATs and VATs alone to survive. You're forced, by sheer weight of numbers, to shoot stuff in first-person. This isn't a good thing.

Your main task is to get off the ship, but initially you're tasked with getting out of the holding cell area. Before you do that though, you meet a surprisingly chirpy little girl called Sally. She acts as your guide throughout, creeping through vents and opening doors as you head towards the bridge. Along the way you gather an eclectic mix of followers, all abductees like yourself. There's an American soldier, a revenge-obsessed cowboy and even a Samurai. Really.

There are a number of alien weapons to loot, including the Alien Atomizer.

Soon you begin to unravel what the aliens, which seem inspired by the aliens from 1996 movie Mars Attacks!, are up to. There's no dialogue involved in this discovery - just exploration. Again, no spoilers. All we'll say is they like abducting people and they like experimenting on them. And not everyone you meet will be from the same space and time you are, although you've probably worked that out from the above paragraph if you've got two braincells to rub together.

For many, though, the new weapons will be of more interest than the plot. All the new weapons are alien, as you'd expect. You first get the Shock Baton, a melee weapon that does okay-ish damage up close. Next it's the Alien Atomiser, a small gun that rapidly spits out energy beams that do good damage. After that you get your hands on the Alien Disintegrator. As a two-handed rifle it's more powerful than the Atomiser, but you can only get a couple of shots off in VATs. This is a problem, because the aliens, particularly the ones that seem to be able to move in and out of phase, are double hard bastards that are incredibly good shots and fast moving to boot.

The alien weapons are a bit of a let down, only because they're not particularly inventive (more powerful variants of the above become available towards the end, but they're basically the same with more impressive stats). About halfway through you get the grenade launcher-like Drone Cannon, which seems to do hardly any damage to the aliens but does play fun havoc with the game's physics (it also reduced the framerate to pitiful levels). The hardcore will be disappointed to discover there are no Alien Blasters to be found, but you can use Alien Epoxy to repair any weapon by 25 per cent, including the Gauss Rifle (yeah!) so it's no bad thing. What is bad is that there are only a few Alien Power Cells to find on the ship. Boo. There's a weapon, not too dissimilar to the Alien Blaster, that you get right at the end that seems designed to make up for this fact, so it's not too bad. More interesting than all of the new weapons, however, is the Samurai Armour. The mere existence of such a thing has already set the Fallout hardcore off. Whatever your take on the issue, it's hard to resist murdering the owner for it.

The main quest is really the only quest. Unlike the superb The Pitt and Point Lookout add-ons, there are no side quests to embark on (that we found anyway). There's an Achievement for finding all of a certain item, but that's your only real distraction. All there is to do is march inexorably towards the top of the craft, killing countless aliens along the way. You're on an absolutely enormous ship, and yet the entire experience feels claustrophobic. Perhaps because there's nothing to do but follow your Pip-Boy way point marker to wherever you need to go next, Mothership Zeta feels remarkably linear and combat heavy, and rekindles memories of Bethesda's first Fallout 3 add-on, Operation Anchorage.

Mothership Zeta has its moments, but they're few and far between.

What's most disappointing of all though, is that there are no big decisions to make, no morally grey head scratchers. There are no real karma affecting choices. You can kill alien workers if you want - innocent bystanders who run away from you, and you can kill your friendly NPCs, but that's not the game asking you to make a decision, is it? As I neared the end I was sure I was going to be asked whether I wanted to avail of what I thought was an obvious game-changing opportunity. I wasn't.

There are some stand-out moments, however. There are a number of holotapes to collect, each with a recording of an abductee being forced by aliens to talk. Some of them are quite funny, especially the one of a sweary Raider. Stop and listen to your gang chat to each other and you'll hear some surprisingly engaging dialogue, particularly when Somah explains the current post-apocalyptic desolation of the world to those who had no idea, including Sally and the soldier. There's a set piece that's like nothing in the game so far - from a raised platform you need to trigger pulsing pylons as drones and aliens run past them - the pylons send the aliens hilariously flying through the air. At one point you embark on a space walk, which is as strange an experience as it is liberating. And the climax to the whole thing is sufficiently different and epic feeling to last long in the memory.

All told though, Mothership Zeta is a let down. It's nowhere near as good as Point Lookout or The Pitt. It's slightly better than Operation Anchorage, but only slightly. It's a linear, repetitive slog through an alien space ship and nothing else. Is it a fitting finale? No. Is it worth 800MS Points? Just. If only for the Samurai Armour. Sniff.