The most original and deliciously deviant character is the Alien. It has no weapons. It has no armor. It merely has its instincts and extremities as a defense. Let me be clear: This is the most agile player character ever in a 3D game. It requires some practice to competently control, but the creature’s abilities to leap great distances and ascend the walls and ceilings is stunning. Just playing around in the first room with all the moves and getting accustomed to the whirling visuals is a pleasure. Rebellion could have fallen into the Descent mode of design and confused players with nondescript corridors and rooms; instead they created floors with distinct textures and programmed the controls to flip the Alien and land him upright should the player become disoriented. The Alien sees the world through a distorted fish-eye perspective and even has a hunting mode that enables him to target enemies in poorly lit areas. Rebellion brilliantly succeeds in placing gamers inside something truly alien and completely unfamiliar. It is another testament to the excellence of the design that after fighting and experiencing death as an Alien, I have a deeper understanding and even a newfound sympathy for the creature. When was the last time a game enhanced your understanding of the film it is based on?

There is a total of 32 solo maps — a solid amount of gameplay. The environments range in tone and setting from bizarre Alien temples that redefine the meaning of vertigo to futuristic military bases. For the most part, the action plays out indoors, though the occasional small outdoor arena offers a welcome respite from the tight interiors. The most notable environmental feature is the lethal sense of atmosphere. The designers have a powerful tool in the engine, which generates the most gorgeously eerie dynamic lighting effects ever seen. Rebellion uses this feature to great effect, setting up situations where lights are timed to pulsate and fade so they lead your eyes down a long corridor to a pinpoint of red — where something very harmful awaits.

The Aliens can actually run through levels destroying the lights, a subtle touch that adds to their credibility as living creatures and threatening opponents. Reflective surfaces, rain, realistic water and in-game videos that relay mission information to the characters add to the immersion and sense of urgency. Populating these maps is a disappointingly limited set of eight enemies. I wish there had been more, though the ones present and accounted for, including the face huggers and the Queen Alien, have forever burned themselves into my wide-open retinas. The animation system used to bring these creatures to life as well as render their spectacular limb-tossing deaths is a gem. Imagine targeting the tail of an Alien or the head of a Predator and affecting their movements. There is even a statistics screens at the end of the missions that calculates such hideous percentages as head shots.

If there is a flaw more pervasive than the nonexistent narrative, it is the game’s unrelenting difficulty. There is nothing wrong with a tough piece of meat, but Aliens vs. Predator is almost too tough. Additionally, Rebellion has amplified this issue by excluding the save game feature — nothing less than a bad decision for this title. The difficulty is too intense and death too frequent to expect players to be patient enough to repeat huge sections of gameplay time and again to complete a map. There are too many random events, such as respawning Aliens, and too many opportunities to endure severe damage. The Alien can be shot down in a flash and the Marine is extremely susceptible to falling damage. The most egregious examples are the timed escape sequences at the end each character’s campaign. It’s tough enough defeating a boss, but then players must escape the map in one minute or die without any prior indication of where the exit is! Boo and hiss. Despite this misstep on Rebellion’s part, the game is wholly worth attempting for the sheer pleasure of the immersive environments and the unique survival experience each character offers.

As fun as the solo experience is, Rebellion and Fox Interactive at long last did something 20th Century Fox never resolved to do: Toss the characters into a fetid deathmatch stew and let them pore over the entrails. Multiplayer is where Aliens vs. Predator truly earns its appellation. It’s also where the character imbalance becomes evident. The Predator, with its near-invisibility and vision modes that transform enemies into glaring neon signs, is too competent. Blend that with the zoom lens and he becomes a tremendous foe. That said, someone with a consummate grasp of the other characters’ abilities could survive and possibly emerge victorious. The Alien can use a potent combination of speed, agility and reverse resource management — meaning it can destroy the powerups available to the Predator and Marine — to succeed. The Marine can rely on his speed and powerful weapons. LAN and reasonably smooth peer-to-peer Internet options are included as are various game options, including deathmatch, tag, co-operative deathmatch against swarms of computer-controlled aliens and a personal favorite, Last Man Standing. The multiplayer aspect will not replace anyone’s deathmatch favorite but is an engaging diversion due to the faithful use of the film licensing.