Aliens versus Predator 2/Alien

Interface

 * 1) Your current health. When it drops to 0, you die.
 * 2) Arrows appear when you activate a wallwalking ability. They show where the ground is. If the arrow is on the top side of the screen, you're upside-down.
 * 3) Jaws appear only when you can bite a head of a foe.

Next vision mode
Switches between your regular vision and night vision. While in night vision, your viewing angle is smaller and arrows don't appear if you're using a wallwalk.

Headbite
When you aim at a head of some human, jaws will appear in the top and bottom areas of the screen. Perform a regular attack to kill your victim instantly and restore a bit of your health. While this attack is really fast, you must aim at the head both when you begin a headbite and when you finish it or it just won't work. You can bite heads off corpses, so use it to your advantage before they disappear. Synthets and predators cannot be beheaded.

Facehug
It's a special attack available only to a facehugger, hence the name. Perform it to make a long jump and kill a target this instant. If you're not too careful you can kill a wrong target and the game is over! Facehug can be performed with a regular attack as well.

Tear
When you come close to an object than can be destroyed, your paws will appear. Perform an attack to tear down human equipment.

Pounce
You make a jump which allows you to cover huge distances finished by a powerful attack. The damage you deal is enough to break a human into pieces. Pouncing will leave you without human corpses, so you won't be able to bite their head off.

Wallwalk
Activate a wallwalk to walk on walls and ceilings. Arrows will appear showing your current orientation.

Leap
While it's not specified in controls, an alien can make a high leap like a predator. Jump while crouching to jump higher (though, not so high as a predator). While wallwalking is usually preferable to reach certain places, a leap is better in combat if you're not used to wallwalking but must act quick and reach an enemy on high ledges.

Weapons
You have but a single weapon which you cannot switch.
 * Fire: Makes a fast and relatively powerful attack with your claws.
 * Alt-Fire: Attack with your sting doesn't deal any damage. It stuns your target instead so you can easier bite a head off it. Remember that aliens and synthets cannot be stunned, only humans can.