This generator does not override the original Alien Invasion Generator, instead it adds onto it.
The Aliens in this case are part of a larger, multi-species of aliens. Roll all relevant tables on the first generator. The aliens generated are the leaders caste of the coalition, and their weapon or fighting style and alien quirk is specific to them. The technology, purpose, and other tables apply to the entire coalition- the lesser castes are augmented by that technology when applicable.
The 'leader' caste is the most politically central of all the castes and controls and directs all other actions. Most of the other castes are clearly modified or eugenically guided to better fulfill their purpose and enhance obedience. Roll once per table to see the castes of coalition.
 Sausages. Filled with green-gray goop and have technological limbs to move.
 Large eyeball, few tentacles as limbs. Bright orange or blue skin, eye has a huge black pupil.
 Crawling, sandy-colored seaweed-like creature. Photosynthetic, takes soil samples by taste.
 Dolls. Look like small doll-like beings, have fake clothes for artificial bodies, etc.
 Dragonfly-like insect people with three sets of wings. The last set is artificial. Can hover.
 Crocodile-like creature. Has robotic arm that drags a tablet computer to its little hands to take notes and interact with any tools they pick up. Usually floats in the water, deceptively intelligent.
 Floating sphere-shaped probes with 'finger' antennae. Small glass port on the back reveals a tiny patch of freely growing nerve cells, which control the probe and give it “personality”.
 Black Orbs of a latex-like material. Float, cling to whatever they touch, scrap samples from the surface of objects. Somehow intelligent, but require communal spinning wheel machines to input data and are fragile enough to be killed by basic weapons.
Soldier Caste -1d8
 Bipedal creatures with blue skin and cube-shaped heads. No eyes, mouth, or nose.
 Fleshy stumps with a few short legs. Spikes grow out as armor. Weapons built into body.
 Tank-Men. Creature born inside tank, never let out, has four powerful arms man the guns.
 Centaur beings with four black stilt-legs and gray vaguely humanoid upper body. Snipers.
 Tall, lanky gray-skinned aliens with snouts that wear collars. Still seem to possess “honor”.
 Cat people. Kind of cute, but as murderous as if cat were actually people sized and had people level of intelligence. Plays with their prey.
 Genetically modified members of the leader caste. Increased size, strength, and metal plates screwed into place over face. Lacks most upper levels of thought or free will.
 Robotic soldiers. Heavy arms and armors, animated via means of the aliens main form of technology. Have a open spot underneath their armor for easy maintenance, means they're very weak to ground based explosives and attacks from underneaht. This is fixed after the second time it is successful exploited by the earthlings, with armor put into place to cover this weak spot.
Hazardous Environment & Worker Caste - 1d8
 Machine with catapult like main body, one major arm for heavy lifting and work. Levitates.
 Ultra thin white stick creature, head is just a stick with a few light detecting spots. Creepy walk.
 Pyrosome membrane worms. Crawl like snakes, can eat anything. Use light to communicate.
 Heavy bloated stone-skinned creature. Silicone based life form. Has lumpy stone 'hands'.
 Neanderthal looking humanoid with purple hair and pale skin. Seems resistant or immune to radiation. 50% chance it shares a common ancestor or it is the common ancestor to man.
 Beetles with green nubs on the side. Can hook into special harnesses to use guns or get prosthetic arms to pick things up with, etc. Similar to a cockroach.
 Dog-sized furry weasels with bulbous sacks on their back. Can inflate them to float on water or move across light surfaces. Can also stand bipedal and draw weapons from holsters in their sides.
 Gnarled plantoids. Look like dead shrubs, roots hook into mechanical walker to move.
Terror Units - 1d20
Every caste has a terror unit, which are only found during terror missions or within alien bases dominated by that caste. Crashed UFOs and away missions do not have terror units. 1 in 4 chance any given caste has 2 terror units instead. Leader caste may have their own terror units or use other castes as their backup.
 Roll a new Science & Exploration Caste alien. It uses brain scrambling devices/psychics.
 Roll a new Science & Exploration Caste alien. Sets up alien equipment on missions that give aliens better battlefield control and zap nearby people who get too close.
 Roll a new Soldier Caste alien. Equipped with heavy explosive munitions & suicide bombs.
 Roll a new Soldier Caste alien. Have very heavy personal armor or energy shielding.
 Roll a new HE & Worker Caste alien. It has an aura of toxic fumes or radiation. Immune to itself.
 Roll a new HE & Worker Caste alien. Fights in close range with highly effective natural weapons.
 Amorphous blob men. Can squeeze through gaps, dissolve people with sludge, split apart, etc.
 Bat creature with ape-like upper arms it walks on. Unusual face lets it channel its own sound waves when it ecolocates; scream temporarily disables human technology like radios, generators, etc.
 Trilobots. Little mechanical bugs, crawl into vents and hide under cars to get close. Stinging people releases a toxin that paralyses them for a few hours, useful to capture and terrorize humans.
 Death Ball. 3 ft Diameter orb, brightly colored plastic. The orb fires the alien leader caste's signature weapon in all directions with great speed and accuracy, firing on the go, and it is almost impervious to damage. Aliens only ever bring one at a time because it's enough.
 Shield Barer. Alien creature with compound eyes and a turtle-like head, body is replaced with artificial shell. Can project an energy barrier up to 20ft up and across or to fill a space, blocks all physical and energy based projectiles. Come along with soldiers as defense.
 Spewworm. Horrible little creature that swallows anything organic, before spitting it back up in a disgusting spew that smells terrible and creates clouds of stink. Vomit also contains baby spewworms, as they reproduce this way. Any area hit is uninhabitable by humans shortly after, only aliens have special frequency weapons that kill spewworms to reclaim the area.
 Heavyset, gray and brown skinned aliens with walrus like faces. They have huge cannons attached to their arm and fire out bolts of green energy that explode things on contact, causing huge destruction and damage. Not given armor or much direction, hitting the generator on their back will blow them up.
 Biological spider-like upper body with a floating set of jets for the bottom. This being is equipped with several scanners and enhanced eyes with glowing red laser cores- they can see through walls and hear tiny sounds like heartbeats. Help aliens locate hiding humans, but aren't armed themselves.
 Skink-like small lizard men. Have special body suits that help them go camouflaged in any environment, partial invisibility. Armed with knives or small pistols for close up assassinations.
 Whatever Caste rolled for this terror unit; a regular member wearing a full biohazard suit with other containment equipment and respirator. Uses a plasma-throwing flame jet gun that melts and vaporizes everything it is shot on. Short maximum range.
 Roll a new Leader Caste alien with their new signature weapon. They are very effective, but seem to be mercenaries or of an intermediate “caste” above the slaves and soldiers.
 Decoy Drones. Appear as something cute and harmless, like a baby in a stroller or a box full of puppies to a 'free home'. The moment it is approached closely it transforms into a robot with metal blades and slices people up close. Only has one decoy form so once discovered and circumvented aliens stop using it altogether.
 Dome-like construction. Waxy glass dome is opaque, and absorbs 90% of all damage dealt to it via energy weapons. The underneath is flat and has a bunch of shiny holes. Floats 8-10 feet off the ground. Attacks by hovering over victims and blasting them with the alien leader caste's signature weapon.
 Human 'zombies' changed via some kind of attached cybernetic, brain parasite, or implanted alien organ. Fight as rage zombies, basically just shock troops. 1 in 20 chance of removing the parasite/implant successfully without killing the human, who can be brought back to normalcy with some interesting knowledge about the aliens they learned while under control.