Natural Selection/Alien buildings

Resource Tower - 15 Resources
Just like the Marine Resource Towers, these guys collect resources for your team. Losing one is not as much of a crushing blow it is to the Marine team, since Aliens tend to have a lot more. Still, they should be protected well.

Offense Tower - 10 Resources
These potent little guys fire spikes that do 50 damage. They are very accurate, and 1 tower can hold off 1 or 2 Marines by itself. Its usually best to put them in groups of 2 or more though, so they can quickly kill any Marines before they do significant damage. You can also stack these on top of one another, but be sure to put the one on top slightly back away from the direction Marines will be attacking from, since the top tower could block the spike from the bottom one. These are the only static defenses the Aliens have, so when in doubt of what to build, spread these guys around. Offense Chambers only do half damage to heavy armor, as of 2.0.

Hive - 40 Resources
The most important building for the aliens. Each Hive allows the aliens to use another one of their attacks, have access to another upgrade chamber, and have another place to spawn. They have quite a bit of life, and the constant influx of players should keep them well defended - a few offense chambers couldn't hurt, however.

"Upgrades" Category
These chambers, in addition to having their own benefits, allow your team to purchase upgrades from them for 2 resources each. Each upgrade has up to 3 levels, represented by 3 or more of the respective chambers. You can only have 1 type of chamber per Hive, and as soon as 1 is dropped, the current Hive is "locked" to that chamber. So if someone built a Sensory chamber in the first 5 seconds of the match, the only upgrade tower you could have and purchase upgrades from is a sensory chamber until the 2nd Hive goes up. So choose wisely, and ask your team which one they want before building one!

Defense Chamber - 10 Resources
These chambers heal any players or structures in their range. They are useful to set up portable "healing stations" at points throughout the map, as well as protecting offense chambers. The upgrades are as follows:


 * Carapace: Increases your amount of armor and damage absorption at the cost of a slightly decreased movement speed. A higher level will increase your armor and damage absorption.
 * Regeneration: Constantly restores your health and armor. A higher level will increase regeneration.
 * Redemption: Once your life drops below the Redemption threshold, which is roughly 30%-40%, the Redemption process will begin. In a few seconds, you will be instantly zapped back to the Hive, saving your life.  A higher level will decrease the amount of time needed to complete the Redemption process.

Movement Chamber - 10 Resources
My personal favorite 1st Hive Chamber, these give you a large energy boost when in their vicinity. They also let you teleport to any built hive instantly by simply pressing use on them. The upgrades are as follows:


 * Silence: Allows your movement and attacks to be silent. A higher level will increase how silent you are, until you are completely silent.
 * Adrenaline: Increases your energy regeneration rate. A higher level will increase that regeneration rate.
 * Celerity: Increases your movement speed. A higher level will increase this movement speed.

Sensory Chamber - 10 Resources
These chambers cloak any structures or players in its area. When cloaked, structures and players are roughly 90% invisible, so you can often run right up to a Marine and slash or bite him while cloaked. Cloaked offense chambers are a nasty surprise as well. Attacking will end the cloaking process. To re-cloak, you will need to stand still for a few seconds. The upgrades are as follows:


 * Cloaking: Unlike Sensory Chamber cloaking, this is only activated while standing still. A higher level will decrease the amount of time you need to stand still to cloak.  You can walk while cloaking and remain so.
 * Scent of Fear: Basically motion tracking for aliens. A very good upgrade, the only good one for sensory in my opinion.  A higher level will increase the detection range.
 * Pheremones: A horrible upgrade, this basically leaves a trail of gas behind the Marines. I suppose you could follow them with that, but Scent of Fear can do this and much more.  A higher level will increase the length of the trail.