Aliens vs. Predator 2
is basically three separate play experiences in one. You can play the game as the Marine, the Predator and the Alien; each of them is a vastly different experience, and one that deserves your attention. They are laid out in the suggested order of play, which is a good idea to follow for plot and experience reasons.
Those of you who played the original Aliens vs. Predator know that the game was disjointed; Aliens vs. Predator 2, on the other hand, tells a nicely-woven tale of a corporate venture gone awry. You'll see things in each of the three campaigns that you saw in the others, only from different perspectives; it really makes for a fascinating experience, and a more absorbing one.
The Marines campaign is the most straightforward, in terms of classic shooters. You've got a lamp to keep yourself from getting completely terrified, along with night-vision goggles; you've got a pulse rifle, a pistol and even a handy knife; you've got your wits and a long, dark journey ahead. Prepare to jump at indigenous lifeforms, and to really jump at the real bad guys; you are outclassed and outnumbered, and it's a hell of a fight to get through. Nonetheless, the experience is quite like any other shooter, if much spookier than most.
Next up is the Predator. Armed with four different modes of vision, some insanely powerful weaponry, and the ability to turn invisible to the Marines, the Predator makes for an interesting experience. It's definitely more complex; the weapons have targeting systems and various hobnobbery you have to deal with. But the Predators are amazingly powerful beings, and this power comes through in the game. Stealth is key, and long-ranged attacks are the norm.
But the most exhilarating experience, by far, is that of the Alien. Starting from a lowly facehugger, you must impregnate a host and come out as a chestburster. Moving from there to the standard drone, you are armed with your tail, your claws, and your powerful jaws. There's no 'ammo' or anything of the sort for the Alien, just a health bar that gives you a hint of how much more damage you can take. You can run along walls, upside down, and all around; this can be extremely disconcerting if you don't know what you're doing, but soon enough it becomes second nature, and running along the ceiling at the Marines is an enthralling ride. The Alien sees with pheromones, which means that machines are invisible to it in the standard mode.
If you don't feel like experiencing the three fascinating (albeit relatively short) campaigns, you can jump into multiplayer. There are a multitude of game modes, ranging from the standard Deathmatch to the more intriguing Survivor (last the longest) and Hunt (one vs. many) modes, and two modes highly reminiscent of Assault from Unreal Tournament--Evac and Overrun. All of these are entertaining, and with the recent multiplayer patch, the experience is solid.