Alien

An Alien is a life state in The Sims 2 for PC, console, and Nintendo DS. Aliens are not featured in The Sims 3, however it is possible to create an alien in Create a Sim.

Biology
Aliens, much like Sims, are an accident of evolution in the sense that they are startlingly similar to Sims to the point in which they both have evolved in parallel with each other and that they can reproduce with one another with no ill effects. Aliens appear to be a hyper-evolved extreme of life, where their species has virtually no variation beyond facial structure and body structure. All pure aliens have the same shade of green skin and have black hair genes and eyes. This suggests that all forms of genetic variation such as recessive genes equivalent to Sim DNA, like light blue eyes and grey eyes, have been selected against to the point where only the most dominant genes have come out on top -- in aliens, recessive genes do not exist. Whether this chance is due to natural selection or due to the alien's social structure is undetermined.

However, shades between green skin and the brown Sims skin tones have not been exhibited, suggesting that alien genes are dominant to the point where all aspects of genetics between Sims and Aliens are "all or nothing" -- meaning it is impossible for there to be an almond colored or olive colored alien-sim hybrid. However it is not dominant to the point where every child produced will be green skinned with black hair and eyes, these genes merely behave as brown eyes and dark do in Sim genes. Although Sim skintone genes behave on a scale where a light skinned Sims and a dark skinned Sims can create a child with fair skin, if any tone of Sim skin and alien skin are involved in the process of creating a child, the chances of either tone showing in the child are 50% -- it's either Sim skin or Alien skin.

As Sims, like humans, are most likely also descended from dark skinned ancestors, it is possible that aliens had a dark green skintone early on in their evolution, assuming that they migrated from a hot climate like Sims and humans did.

"Hyper-evolution"
Aliens only have dominant genes, and universally detrimental personality traits such as shyness and sloppiness have been selected against, most aliens have "perfect" personalities, such as Pollination Technician, who can father hybrid children with partially perfect personalities; but some aliens have more varied personalities such as Pollination Technician 9 Smith. This "hyper-evolution" suggests that aliens have been sentient for a lot longer than Sims have, which more obviously manifested in the far more advanced technology that allows space travel.

Pure alien
In the most literal sense, "alien" would refer to the pure aliens. These creatures are the outlandish visitors that come from another planet that abduct the player's Sims during the use of an expensive telescope.

Appearance
Pure aliens always have the following features:


 * Lack of hair (except Pollination Technician 9 and Stella Terrano)
 * Green skin
 * Large, dilated, black pupils
 * Pointed ears (Pre-made neighborhood Canon)
 * Small ears (Custom neighborhood Canon)
 * Long, gaunt faces
 * Small, flat noses
 * Black hair genes (except Pollination Technician 9 )

Social caste
From what little information is given from the family history of Pollination Technician 9, a player can see what appears to be a social caste among the lives of aliens on their home planet:
 * Birth Queens are the central reproductive system of the aliens. It appear that whomever impregnates them has no marital attachment to them, and that the sole life purpose of a birth queen is to breed.
 * Colony Drones are the workers of alien society. They appear to serve their overlords similar to worker-bees.
 * Pollination Technicians are the aliens that pilot spacecrafts seen from telescopes and can somehow impregnate male Sims, which will in turn give birth to alien-Sim hybrids.

Reproductive System

 * Natural Reproduction occurs when a colony drone or another male alien impregnates the female of the species, the Birth Queen
 * Pollinational Reproduction occurs when an adult male Sim is abducted while stargazing with the Farstar e3 telescope, and he returns pregnant with an alien baby. This baby can be very unique, and is known as an Alien-Sim Hybrid.

Alien-Sim hybrids
This is the other term that could define "alien". These Sims are playable and are what is defined as one of the many Sim "life states".

Appearance
When transitioning to toddler, alien-Sim hybrids may express facial features not usually found on normal Sims (for example, Flamenco Caliente's high cheekbones). These attributes can then be passed on when the alien child grows up and reproduces.
 * Almost always has a flat nose, some even have a dent where the nose should be.
 * Almost always has light green skin (Flamenco Caliente and Jill Smith are two exceptions)
 * Usually has large, dilated, black pupils (though not always, see Johnny Smith)
 * Usually has curved, normal Sim ears
 * Always has blue gums

Advantages and uniqueness
This is possibly the simplest of all life states. Unlike pure aliens, alien-Sim hybrids are treated equally with other Sims and reproduce the same, as well. Advantages of having a hybrid include a unique skin tone and facial features. A unique feature to their birth is that when the child is born a different cinematic is used. Another unique feature of alien hybrid Sims is that they have personalities that tend to the extremes in each area. A final feature is the missing WooHoo, the missing partner, and the male pregnancy.

Aliens are usually found in Strangetown for the personal computer, whilst console versions has them inhabiting Strangetown and Pleasantview.

How to become impregnated by Aliens
There are five ways to become impregnated by Aliens. Two ways are legitimate and three ways are via cheating, which poses a risk of the game being damaged if debugging tools are not used.

Normal Gameplay

 * Telescope - A male adult Sim can stargaze with the Farstar e3 telescope until he gets abducted. The chances of this are at a modest 0.05%, which remains this way unless manipulated by mods or hitching a ride with the FreeTime aspiration point bonus. After the Sim is abducted, they will return a few hours later, pregnant with an alien hybrid.


 * Electro-Dance Sphere - If the player has the Nightlife Expansion Pack, male Sims can also be abducted using the machine if they have been abducted previously with either 2 telescopes, or if very lucky, the Dance Sphere. It is rumored that the the chances increase if a Sim uses the Dance Sphere with 10 Body points. This method varies in effectiveness between 1.65% to 2.5% depending on how many times the Sim has been abducted previously, but the chances are significantly higher than a telescope, regardless of how low it can get.

Cheating

 * In-game Debugging Mode - Entering the cheat  then shift-clicking on the telescope and choosing "Debug - get Abducted". After this point, the process continues as normal. Newer expansion packs have made this cheat impossible. All the Sim will do now is walk up to the telescope and cancel the action.


 * The Tombstone of L & D - Initiating the  cheat, then, shift-clicking on any Sim and spawning the Tombstone of L & D (Life and Death) allows the player to open up testing options to initiate quick pregnancy in any gender. The options "Make me alien pregnant" and "Speed up my pregnancy" in the pie menu make this the fastest, albeit riskiest method of all. Both options will work regardless of gender and age above adulthood.


 * Create-A-Sim Debugging Mode - Enabling the  cheat allows the player to hold Shift+N to unlock alien skintone and eyes, along with hundreds of other features hidden by the game in CAS. It is turned off by holding Shift+M. This method of cheating is the safest, as there is minimal opportunity for the game to crash as it likely would in normal gameplay. Furthermore, CAS only creates Sims without any varied recessive traits or extreme personalities that would be inherited with normal hybrids, although these values can be edited by those knowledgeable enough to change these values in programs such as SimPE.

The Sims 2 console versions
The player can create aliens by randomizing appearance in The Sims 2 for console. All aliens have at least 1 alien in their family tree.

The Sims 3
Aliens are not featured in The Sims 3 base game (or any expansion pack to date) however it is completely possible to create them. Additionally, subtle differences in green skin tone can be made, which wasn't present in The Sims 2.