From the back of the package:
HUNTER. SURVIVOR. PREY.
Three breeds of warrior.
Three brutal campaigns.
One relentless multi-player battleground.
Survive the horror with three playable species.
Aliens vs. Predator is a science fiction first-person shooter video game, developed by Rebellion Developments, the team behind the 1999 original PC game, and published by Sega for Microsoft Windows, the PlayStation 3 and the Xbox 360. The game is based on the Alien vs. Predator franchise, a combination of the characters and creatures of the Alien franchise and the Predator franchise. It was released February 16, 2010 in the US, February 19 in Europe and February 18 in Australia.
There are three campaigns in the game, one for each race/faction (the Predators, the Aliens and the Colonial Marines), that, while separate in terms of individual plot and gameplay, form one overarching storyline.
Following the storyline of the campaign modes comes the multiplayer aspect of the game. In this Multiplayer section of the game, players face off in various different gametypes in various different ways.
As in the films, the Predator prefers to stalk its prey from the safety of treetops and the gameplay reflects this, the player leaping from branch to branch automatically with the help of a "focus jumping" game mechanic. The Predator has different vision modes, the most recognizable from the films being a thermal imaging scanner, but the player also has different vision modes for spotting Aliens (only accessible from a special mask the player picks up in-game) and viewing the world normally. For example, the Heat Vision mode allows the player to see marines, even at a distance, crystal clearly, while it renders Aliens nearly invisible, the Alien vision working in reverse, and regular vision seeing the environment and other predators better than the other two, making battles between two or all three species a tactical juggle to prioritize enemies based on their threat to the player.
Aliens fight in close-quarters with their claws and tails, getting as close as possible to their prey as quickly as possible. Aliens have the ability to climb walls and jump from distances without effort, and can blend in with shadows, using darkness to their advantage. Within limited ranges, aliens can seek out prey through walls. These senses also allow Aliens to clearly observe cloaked Predators. In the single player campaign, players will have the opportunity to harvest 'hosts'. By pinning the host, nearby facehuggers are able to locate and latch on to them, thereby propagating the Hive. Throughout the game, the player also has the opportunity to perform 'Stealth Kills'.
The Colonial Marine campaign is far closer to that of a standard first-person shooter. Marines carry a wide arsenal including pulse rifles, flamethrowers, and auto-tracking Smartguns. To help navigate the surroundings, marines are equipped with shoulder-mounted lamps, surveying flares to briefly illuminate darkened areas, and motion trackers, capable of providing info on hostile positioning as they move.
Source: Wikipedia, "Aliens vs. Predator (video game)", available under the CC-BY-SA License.