The Aliens are one of the factions in the Earth series. So far, they have only appeared in Earth 2160.
The term "Aliens" is a general name for many alien species from many diffirent "families".
Not much is known about the Aliens' history. What is known, is that they were asleep underneath the surface of the planet Eden. How they got there or where they came from is a complete mystery.
It is speculated however, that the ancient race referred to as the Builders are responsible for the Aliens creation, using them as an army of sorts. It seems however, that when the Builders left Eden, they also left the Aliens in stasis beneath Edens' surface.
When the Lunar Corporation inadvertantly releases the Aliens, they rapidly spread to overtake Eden, and many other planets besides.
Unlike the other factions, the Aliens do not build bases or train units. Instead, they clone. The basic family of ground units is the Mantians, including the Mantian Lady, Princess and Queen. Each different species of Mantian is capable of mutating into a certain type of offensive unit.
The Mantian Lady can mutate into Formidian Troopers, a basic land unit, as well as several different immoble "turrets".
The Formidian Trooper can evolve into a Formidian Guardian, a larger version with more HP and attack strength
The Mantian Princess is capable of becoming a Hermipterean Grenadier or Defender, the grenadiers job being to act as artillery, while the defender acts as an incredibly powerful anti air system.
The Mantian princess also detects almost all ground movements, acting as a sophisticated sensor, warning of any land units in a large radius .
The Mantian Queen can mutate into the Coleopian Tank, as well as an anti building unit. It is also capable of "de-evolving" into a Mantian Lady in case the player loses all their Ladies.
The Coleopian tank is a powerful anti-vehicle unit, which can become either a stronger anti-vehicle unit or a powerful anti-organism weapon (essentially a giant psychic brain that kills infantry and pilots)
The Aliens have by far the most dangerous air units in the game. The Replicatorus is designed only to clone itself or become a Morphoratorus, which is the base for all Alien Aircraft. The Morphoratorus can become either a group of 4 Postomor Fighters or a powerful warship. The Warship can then evolve into either a bombardment unit, or ludicrously powerful attack vessel. It is reccommended to use at least 40+ anti air weapons when facing even one basic alien vessel.