IMPORTANT NOTICE! The following preview contains SPOILERS relating to the ending of Fallout 3. Consider yourself warned.

Everybody makes mistakes. I do, you probably do, and game designers most certainly come a cropper from time-to-time. We're all human, after all. The important thing is to learn from your past errors, and to fix your missteps wherever possible. Now, with its forthcoming Broken Steel DLC expansion, Bethesda is addressing one of the biggest flaws of Fallout 3: it's rewriting the messed-up ending.

As anyone who's played the game will attest, Fallout 3 is a game of choices. At any given time you can decide to be a hero of the post WWIII wastelands, a psychopathic villain, or perhaps someone just trying to survive; you can choose to do the right thing, the wrong thing - or even just the most profitable thing. This freedom helped to make Fallout 3 one of the most absorbing experiences of 2008 which is why quite a few people felt rather short-changed by the game's brief and surprisingly restrictive conclusion. In a nutshell, the climactic do-or-die task involved entering a sealed room chamber to enter a code into an unstable water purifier - the catch being that the room in question was flooded with lethal levels of radiation.

It was one hell of a sticky situation. You could go in yourself, or you could send in a young woman named Lyons, but either way one of you was doomed to become glowing wormfood (unless you did nothing, in which case everything blew up and you both died). These three choices also came in "Good" and "Evil" flavours, depending on whether you chose to infect the water supply with a nasty virus, but the end result was always largely the same: a brief slideshow accompanied by a rather preachy voiceover... followed by a wave of crushing disappointment, as you realised that post-ending exploration wasn't an option. Game over man, game over.

Now, after what seems like an extremely long wait, you'll soon be able to resume your patrols of post-apocalypse Washington DC. Or at least, you'll be able to provided that you're not playing the game on a PS3 - like Bethesda's previous two DLC expansions, Operation Anchorage and The Pitt, Broken Steel is only coming to Xbox 360 and PC. This time around the exclusion may be a particularly bitter pill to swallow, since this third DLC pack will also extend the game's much-lamented level cap, giving fans a whopping 10 extra experience levels to grind through.

One of the really irritating things about the water purifier dilemma was that it wasn't strictly a difficult decision. Most players reach the end of Fallout 3 whilst accompanied by a friendly mutant named Fawkes - a companion who just so happens to be radiation-proof. Bizarrely, Mr Fawkes would refuse to help you out, making some lame excuse about "not interfering with your destiny" - when he said this to me, I immediately unloaded a shotgun into his face. Once Broken Steel is installed, he'll suddenly be more than happy to oblige. In fact there are three companions who'll be able to input the all-important code for you, and if you go in to the chamber yourself you'll still be able to survive. The only situation in which you'll still die is if you sit around doing nothing, and now there's very little reason to do so.

The Tesla Cannon in action.

Broken Steel properly begins some time after the explosive events at Project Purity. After a brief spell in a coma (cause currently unknown) you come to and discover that there's still much work to be done. The purifier is now up and running, but getting clean water out to the inhabitants of the wasteland is proving to be a harder task than expected. The scientists working on the project need a bit of help with things, and any help you can give will be highly appreciated. A new selection of side quests dished out at the facility will allow you to continue the work that your father started, but this is merely a diversion from the meat of the action.

As its name suggests, this final DLC pack is mostly concerned with the Brotherhood of Steel and their ongoing efforts to combat the fascistic Enclave. The bad guys are down but certainly not out, and the Brotherhood have concluded that they need a new weapon if they are to turn the tide of battle in their favour. To this end, they send you out on a quest to acquire the plans for the Tesla Cannon - a sort of energy-based rocket launcher that fires out glowing balls of electric death. To retrieve the blueprints for this weapon you'll have to journey through the Presidential metro tunnels beneath the ruins of the White House, eventually reaching Adams Airforce Base, a new location that exists separately from the rest of Fallout 3's game world.

It probably doesn't spoil anything to say that finding the plans, and all the quests that follow, will involve lots and lots of fighting. Bethesda says that the ten extra experience levels you can work through will have large XP gaps between them, so it'll take plenty of scrapping to improve yourself. Naturally the increased character progression will mean you'll be more powerful than ever, gaining access to all the top-end perks as well as several new ones created for the DLC - including one that lets Dogmeat "have puppies" (ie. he'll respawn after he dies). Considering that most players are already as mean as the Predator with a toothache by the time they reach level 20, it's just as well that Broken Steel will throw a whole bunch of new enemies at you.

It would seem that most of these new threats take the form of beefed-up versions of the nasties we've already seen. There's the extra-tough Supermutant Overlord, and the Feral Ghoul Reaver, capable of throwing grenades (which seems a bit weird, really). Naturally the Enclave also receive a boost too, gaining the services of the Hellfire Trooper - a pleasant chap whose weapon somehow shoots flaming bolts out in a fearsome ark of crispy death. The new tougher enemies won't start showing up until you've hit level 18, but when they do they should hopefully put up a seriously strong fight. Of course, you'll be getting access to new weapons to combat these foes. The Trilaser is a powerful energy weapon with an extremely high rate of fire, as well as a knock-back effect capable of lifting enemies clean off their feet. And let's not forget the Tesla Cannon: in the demonstration I was shown this was used to take out Enclave Vertibirds with a single shot. The resulting explosion was enormous, so hopefully shooting down these vehicles will be as satisfying as when you take on a Behemoth.

While Operation Anchorage was something of a letdown, The Pitt was quite a fun addition to Fallout 3, so hopefully Broken Steel will continue the upward trend and turn out to be the best of the three DLC packs. The new level cap and fixed ending will certainly be exactly what a lot of fans have been waiting for, but we'll have to judge the rest of the content when we've actually had a chance to play it ourselves. Bethesda says that it will a bit longer than the previous expansions - offering four to five hours of gameplay for the main quests alone, not including the side missions and other content. At 800 points, it should therefore be pretty good value - provided that Bethesda manages to ensure it's bug-free this time around. The Pitt was riddled with technical issues on its initial release. After all, we all make mistakes... but to make the same mistake twice would be unforgivable.

Fallout 3: Broken Steel will be out on PC and Xbox 360 at some point in the near future.