History
Alien: KIT for short, was inspired by this very simple map "Alien" which I did not make, but I did improve slightly, taking no credit for my work until now. For the absolute original, see the attached ALIEN.scm. For my final touched up version see the attached ALIENv9.scm which is very playable.

The original Alien map had a few bugs. Because of Dark Swarm's size, civilians on the edge could never be converted to aliens. I also made the Alien Queen (defiler) starting energy equal to a value based on the number of total players, so that it would be somewhat balanced with 5 to 7 players. The original Alien map had no abilities except the Terran Medic's Heal/Restore/OpticalFlare and the Zerg Defiler's DarkSwarm/Plague. Dark Swarm was used to convert Terran Civilians scattered around the map into aliens. There was no burrow and the only way to kill the alien queen was to trap her. Key strategy involved spreading out in the beginning to find the Alien Queen quickly before it built up a huge army, and then having one human go around a back/side path during a chase and block a chokepoint to achieve a trap of the Queen. For the Alien Queen to be successful, killing the medic was usually a priority. Also delaying/blocking chasing humans with zerg minions and micro was important. Plague was especially effective on the Medic, she could not restore herself.

Alien: Kill it Team!
Alien KIT maintains the team structure of the original Alien map in that there is always 1 Alien Queen (Zerg Defiler), 1 Officer (Protoss Zealot), 1 Medic (Sarah Kerrigan This Time) and the rest are Soldiers (Terran Marines). The actual assignment of these roles is random however. Please make sure you see the Strategy section. Alien KIT does away with the converting of civilians, but adds many interesting features which the Strategy section best emphasizes.

Screenshots

Role assignment


Spreading out early on to search for the Queen - See Strategy section way down below


Queen using Burrow and Broodlings to distract the Soldier


A Soldier checking for Burrowed units in the area. Unfortunately we walked by the Queen long ago lol.


A Medic using Defensive Matrix on the Officer.


A Soldier RUNNING FOR HIS LIFE and using his 10 Gas "Call For Support" ability.


We'll get through this together.

Another major battle.


Typical chase situation. These dont usually last very long. See Alien Queen Strategy way down below.


Alien using its' 75 gas "Alien Mobility" move to end the chase. Note the communication/ping by a human for his teammates.


Uh Oh! Trouble for the Alien Queen! White did a nice stun, then blocked the hallway the Alien was headed to.


Many stuns resulted in a victory for the Human Team... this time. The other replay, Alien wins! I often win as Alien


Map Layout


Abilities
In Alien KIT every Role is important. Every role has 4 abilities. The Humans' Team is incomplete without an Officer, or without a Medic, or without atleast 1 Soldier.
The abilities are controlled from a Protoss Stargate, fairly similar to Temple Siege, with the following vespene gas costs:
Scout 10
Carrier 20
Arbiter 45
Corsair 75
Max gas for all players is 100 and regerates at 1 per second (12 hypers), except the Alien Queen. Her gas regeneration is based on the # of players present at the start of the game and does not change if people leave or die off. Here is a chart:
# of Players | Starting Gas For Alien Queen | Gas Regeneration (Hypercycles for 1 gas)
-----------------------------------------------------------------------------------------------------------------------
2 | 0 | 18
3 | 0 | 12
4 | 0 | 10
5 | 20 | 8
6 | 40 | 7
7 | 80 | 6

Alien Queen (Zerg Defiler)
10 Spawn Minion. A random unit is spawned. Can be Zerg Zergling, Zerg Broodling, Zerg Drone, Zerg Hydralisk.
20 Ensnare. A Zerg Queen is made available for 5 seconds so you may use Ensnare. (you can pre-hotkey it inside its' buffer box btw)
45 Alien Kamikaze. An Infested Terran is spawned. Has considerable HP and Damage.
75 Alien Mobility. A Zerg Devourer is made available for 8 seconds. The queen dodges attacks and moves with the Devourer.
*Dark Swarm. (150 Energy) The Alien Queen can cast normal Dark Swarms for defensive or offensive purposes.
*Consume. The Alien Queen can consume it's own minions to replenish energy faster for more Dark Swarms.

Officer (Protoss Zealot)
10 Knife Attack. A dozen of 1 damage hero zerglings unburrow under the Officer for a moment. I know it's a TS ripoff.
20 Place Mine. A spider mine is placed under the Officer.
45 Flamethrower. The Officer becomes an invincible Terran Firebat for 5 seconds. The damage isnt huge, but youre invincible.
75 Disable. The Officer must be near the Alien Queen. She is prevented from casting spells, is slowed 50%, and does not gain mana for 9 seconds.

Medic (Sarah Kerrigan)
10 Heal. A medic is summoned for 3 seconds with energy to heal up to 24 hit points under the most favorable conditions. Can also Restore or Optical flare.
20 Short Term Cloak. An arbiter is summoned for 5 seconds. The medic is slowed 50% and her movements can still be seen, but she is cloaked. *See Note
45 Defensive Matrix. A science vessel is summoned for 3 seconds with energy for one Defensive Matrix.
75 Maelstrom. A dark archon is summoned for 5 seconds with energy for one Maelstrom.
*Note: if the Medic is Ensnared, or affected by a Defensive Matrix, the Cloak is completely ineffective.

Soldier (Terran Marine)
10 Call For Support. All your human allies get a text message, a sound, shared vision for 5 seconds, and a series of 3 minimap pings on you over 5 seconds.
20 Sensor Sweep. A protoss observer is summoned for 3 seconds. The purpose is to scan for burrowed zerg units including the Alien Queen herself.
45 Heavy Rifle. The Soldier turns into an invincible Terran Ghost for 1.25 seconds. Can one-shot Zerglings, Drones, and perhaps most importantly Broodlings.
75 Stun Pulse. All zerg units within a small radius around the Soldier are stunned for 5 seconds.

Strategy
Alien Queen Strategy: (Zerg Defiler)
-If you choose to research Burrow, using it in unlikely places can help you stay undetected. Burrow also allows for various ambush tactics.
-Spreading out your spawned minions for map vision can help you tremendously in keeping your Alien Queen safe.
-Building up minions in various places for later use will let you overwhelm the human team.
-Attacking the humans from multiple directions in a pincer move increases your chances of success
-As humans split up to search for you, it becomes easier to overwhelm them. Trapping a lone marine or medic with melee units and a Dark Swarm is an ultimate alien success.
-Use of Alien Mobility is essential if your Alien Queen ends up surrounded.
-Use of Ensnare helps you outrun the enemy, or chase down and overwhelm a lone opponent split up from the party.
-Sending a minion ahead of your Alien Queen to clear potential spider mines helps you maintain your Alien Queen's hit points.
-Broodlings and Infested Terrans can actually clear mines and survive the blast.
-Drones do not set off mines. A unique property among the units featured in the map. They can actually "block mines" or "jam them" if positioned correctly.
-Use of unit stats' strengths and avoidance of weaknesses:
Broodlings are most annoying to the Medic, and somewhat to Soldiers.
Drones and Hydralisks have a higher damage, making them better choices vs. Officer who has 1 armor
Zerglings and Drones are fast scouts
Broodlings and Zerglings can attack within Dark Swarm. Contrary to some people's beliefs Drones cannot.
-Hydralisks can shoot over walls
-Unit Micro which produces "Surrounds" when you have many minions
-A combination of burrowed units unburrowing around an enemy, plus a dark swarm immediately after is a nice ambush style way to kill of part of the human team.

Human Team General Strategy:
-In the Early Game, spread out and find the Queen ASAP before a large army is saved up. If the Queen rushes Burrow Research she won't have many minions if any.
-While scouting is done alone, fighting is best done together. A human team working together can kill a great deal of alien minions.
-Eliminating "saved up" groups of units stashed away before the Alien Queen makes a huge assault.
-Blocking thin parts of the terrain so the Alien Queen can't escape from a room or hallway section.
-Use of chat to communicate. For example in the early game, say "i'll scout the left side" or "I'll scout the middle rooms". This way you can cover the map nicely.
Other examples of communication is... when a lone scouting Soldier uses "Call For Support" and you see he's running from a big group of zerg units, tell him which way to run to reach you for help and/or heal/shield.
-Use of pings to incidate aliens locations, especially the Queen and which way she's going so someone can go around and block her, stun her...
-Focus fire on the same broodling when fighting them and they will die fast. Broodlings are high armor low hp and are a pain in the butt.

Soldier (Marine)
-Soldiers are particularly "Scout Roles" as their "Call For Support" is designed for it.
-Checking for burrowed units, especially to find the often burrowed Alien Queen, with "Sensor Sweep". Basically if your gas is full (100) use a Sensor Sweep.
-Soldiers can even reveal things over walls for their allies by comboing "Sensor Sweep" + "Call For Support" which shares vision.
-Soldiers can shoot things over walls with their "Sensor Sweep". They can combo "Sensor Sweep" + "Heavy Rifle" to pick off a unit.
-Use of the "Heavy Rifle" defensively if a large amount of minions are all focused on you in a team fight.
-Use of the "Heavy Rifle" vs. a broodling since it has high armor and low hp... its very annoying to Medic and Soldier.
-It is actually possible to time your "Heavy Rifle" and become the invincible ghost just as an Infested Terran explodes beside you, and you come out full health while the Alien is down one expensive Infested Terran
-Stunning the Queen often leads to victory. Another player can stun just as the first stun ends while the whole team does severe damage to the Queen.

Medic (Sarah Kerrigan)
-Check your allies' HP frequently and use heal when appropriate
-Dont heal like 1 or 2 hp of damage unless you have full gas (100).
-Optical Flare the Alien Queen
-Use Restore on allies and/or yourself if Alien uses Ensnare.
-Use Restore if you accidentally hit an ally with a Maelstrom.
-Give an ally a Defensive Matrix ahead of time if you have full gas (100).
-It's usually better to Defensive Matrix your allies and not yourself.
-Use Defensive Matrix on the Officer specifically if there is a Dark Swarm.
-Use Defensive Matrix on whoever the alien focuses and tries to kill in a team fight.
-Use Short Term Cloak if the Alien player focus fires on you in a team fight, and you are not Ensnared or Def.Matrixed.
-Maelstrom requires careful consideration and restraint. As it is the Medic's 75 it precludes you from doing alot of anything else if you use Maelstrom, and you need to heal your allies alot sometimes. Maelstrom can also affect your allies so misclicking a Maelstrom can be ultra bad. Maelstrom has two key advantages however: It lasts quite a bit longer than a Soldier's 75 "Stun Pulse", and it has the unique property of being able to stop the Alien Queen's 75 "Alien Mobility" in transit because the Devourer is not invincible.

Officer (Zealot)
-You have 1 armor. You should generally be tanking for the team, but not to a suicidal extent.
-You are the only one who can walk into a Dark Swarm and kick ass. Try to unblock any teammate who is trapped by zerg units in a Dark Swarm.
-Because of broodlings' High Armor, Low HP, your "Knife Attack" with the many 1 damage Lings is particularly effective vs. Broodlings.
-When you have full gas (100) lay a spider mine.
-Spider Mines not only can kill alien minions, more importantly they provide you vision of the map. Place them strategically and ping if you see Alien activity.
-Spider Mines can will attack burrowed units if placed close enough. Make sure you notify allies if, immediately after placement, your mine moves, explodes, and you see no blood. It's either an Infested, or the Queen herself!
-If the Alien Player focuses you in a team fight, your "Flamethrower" can be used to prevent you from dying.
-It is actually possible to time your "Flamethrower" so that you become the invincible firebat just as an Infested Terran explodes beside you, and you come out full health while the Alien player is down 1 expensive Infested Terran
-Disabling the Alien Queen can give your team the edge in a chase.
-Disabling the Alien Queen just before she would normally use Alien Mobility such as in a "room trap" or "surrounded" scenario is particularly devastating.

Strategy For ABSOLUTELY EVERYONE
-Pre-emptively Hotkey your ability units down in the bottom part of map for fast use once they are summoned. This is most crucial for the Medic.
-Anticipate the enemy's moves. A good alien will distract people with minions, lead them away from the Queen, and generally just "mind game".
A good human team will try to physically block the Alien Queen to get some good damage on it and force it to use alot of gas on "Alien Mobility".


Replays
I have two three replays of good games of Alien KIT which prove that it contains interesting gameplay as well as balance.
Although the current version of the map is 1.26, you need version 1.24 to see these replays.
Download these 3 files:
AlienKIT124L.scx
ALIENprohumans.rep
EPIC ALIEN OMFG.rep
Alien VeryGGguys.rep <--- NEW! Made 09-August-2011 with xjvioafjsaof hosting! Alien Queen wins with less than 10% HP! Close, intense, balanced! This replay was made in version 1.26

Notes on experinces with Noobs/Random Pubs... Balance...
I've hosted Alien KIT publicly a few hundred times by my estimate. Alot of games, if the player who is assigned the "Alien" role is new... they will suck bad and it will seem like it is impossible for Alien to win. On the flip side if you have a very competent alien and a human team of mostly new players, it can be absolutely brutal for the humans. Yet on an equal skill level the game is quite balanced, deep, and interesting, as shown by the 2 replays.