Update: I was unfortunately not aware of Shamus Young's severe criticism of Fallout 3 available here to link in the original piece and I regret that. It dovetails rather nicely with what I've written and it's much better executed than my piece. I strongly recommend anyone...
Alien Vs Predator 2 is a very cool game. Generally, in a first person shooter, you only get one campaign and play as one person. DOOM doesn't have you playing as an imp trying to kill the marine. Halflife only had multiple campaigns as the extras are in expansion packs. In AvP2, however, you get 3 campaigns in the box from the start.
The first campaign is the Marine campaign. Well, when I say first, I mean it is most likely the one FPS veterans will play first. In this campaign, you are a marine sent into this area as a scout party, sent in to find out how everything has gone so totally wrong. But then everything goes so totally wrong for you. Long story short, you blow stuff up. Or burn it. Or ventilate it with an assault rifle. Or shotgun. Or pistol. Or minigun. Standard FPS stuff. What isn't standard is the fact you are outgunned! Both the aliens and predators are a lot better equipped than you. The aliens have a lot of cool abilities, such as wall walking and pounce-&-kill. The predators have stealth, long range and general technological advantages. All you get is a motion tracker, armour and a flashlight. And your big pile of guns. That'll do.
Once your done with that, you might try the Alien campaign. This is a cool campaign as you go through all 3 stages of Xenomorph growth and development. You start off as a facehugger, then you facehug, you eat your way out of a guy's chest as a chestburster worm, then you eat some small creatures, and then you really get annoyed. For, once the drone stage is reached, you become one angry alien. Killing marines is the order of the day, with a predator added for good measure. Low on health? Eat your victims head! Cool, in a gross sort of way.
Lastly the Predator campaign. This is where you'll likely get really smug. For, the Predator has a device that changes charge for health, and another that freely generates charge. This means that you have absolutely no reason not to go to the next gunfight without max health. What's more, you get the infra-red vision the predators have in the movies, and a new vision mode which allows you to easily see aliens. And yet another one for seeing predators well. And the guns? Well, every weapon you get is brutal and effective. I prefer the Bone gun, as you can collect expended rounds for re-use as long as you get to where you buried it into the wall. Being a predator, collecting heads is the focus, and you have lots of ways to do it. You could decapitate them with the bone gun, or take the head off a corpse with your claws or staff. Brutal.
And once all three campaigns are done, you'll notice the repeats. For, some events that occur in one campaign can occur in the others. For example, as the predator, you have to at one point jump onto the top of a dropship. Doing so triggers some radio dialogue. But, if you play as the marine, you hear that dialogue in that room! What's more, you can actually watch the predator jump onto the dropship, while still playing as the marine. Wicked. At one point, all three campaigns are in the same room, kind of. The predator gets captured and put into a stasis pod. Drifting in and out of consciousness, you as the predator watch as the marine you play as in the campaign works on the console, and then you watch you as the alien pass by. Ultra-wicked.
Alien Vs Predator 2 is a really cool game just because of this intertwined storylines, but with the expansion pack, you get three more that are intertwined, some with those in the regular game! Amazing!
I recommend Alien Vs Predator 2 for any fans of the movies, and for any FPS fans. Casual gamers should look at it too.