Alien abduction

Alien abduction is an event that can happen in The Sims, The Sims Bustin' Out, The Sims 2, and The Sims 2 (console) It can happen to a Sim who is using a telescope to stargaze at night. Every one of the abducted Sim's motives go haywire while they are on board the craft, and they return a few hours later. It is currently not available in The Sims 3, but will return in The Sims 3: Seasons.

The Sims
In The Sims, alien abduction is only possible when a Sim uses the "Gaze" option on the Horrorwitz "Star-Track" Backyard Telescope introduced in Livin' Large. If a Sim uses the telescope at night, there is a low chance that the Sim will be abducted by an unseen UFO. A blue sphere will appear, and the Sim will vanish.

When a Sim is successfully abducted, all family members on the lot will run over to the area of abduction and cry. While the Sim is abducted, their needs will stay static and their personality is changed, as well as their interests. After a few Sim hours, the abductee will return and will immediately think of aliens and spaceships in their thought balloon.

The Sims Bustin' Out
In The Sims Bustin' Out, an abductee will return after about 8 hours with a changed personality. This might, or might not, work in the player's favor. It could be a way of changing stats that the player regretted having given the Sim, or it might drastically alter certain categories that the player sees as favorable; e.g. from very neat and not outgoing to not neat and very outgoing.

The Sims 2
In The Sims 2, Sims will only be abducted if they are using the Farstar e3 telescope. If the abducted Sim is an adult male, he will always come back pregnant, so long as he is more than 5 days from becoming an elder, and there are fewer than 8 household members when he is abducted. In three days, he will give birth to a half-alien baby whose other parent is the unseen NPC Pollination Technician. Other Sims will not be affected, though Knowledge Sims will gain a positive memory of having met aliens, or of the abducted Sim having met aliens, while other Sims will gain a negative memory of the abduction. Additionally, to be abducted (or have a relative abducted) is often a want for Knowledge Sims, and a fear for others. If a Sim is abducted more than once, he or she will get a separate memory for each abduction. The odds of being abducted are very low, on the order of 0.05% percent for each animation cycle.

The abducted Sim's motives will fluctuate wildly until he or she is returned. After several Sim hours, the UFO will appear, hover above the street, and unceremoniously drop the Sim onto the street. Other Sims and pets on the lot will come to watch, at least if they are awake.

If the Nightlife expansion pack is installed, a Sim who has been abducted at least once may be abducted while using the ElectroDance Sphere on medium or high, even if he or she was a teen when abducted the first time. Each Dance Sphere will only trigger one abduction, but the odds of abduction are much higher than with the telescope. In FreeTime, all telescope actions carry a chance of alien abduction, but the top aspiration benefit for the Knowledge aspiration, Summon Aliens, allows a Sim to create a spotlight with a flashlight and telescope, which greatly increases the chance of abduction. This benefit can be used with the Astrowonder telescope. However, is a Sim is abducted while using this benefit with the Astrowonder telescope, the animations which show the Sim being abducted will not play; the Sim will simply vanish.

If University is installed, a teen who has been abducted can apply for the Extraterrestrial Reparation Grant, which is a §1500 scholarship.

Aliens are very important to the Strangetown story (especially with The Curious Brothers), but play a lesser part in Pleasantview - except in the case of Bella Goth and the Caliente Family.

If you want a Sim to be abducted, use "boolprop testingcheatsenabled true", then shift-click any telescope, and select be abducted. This cheat does not work after Seasons, Nightlife, or Bon Voyage is installed. It also will not result in the Sim having the memory of alien abduction, but will still result in pregnancy for male adult Sims 6 or more days away from the elder stage.

The UFO in the game is based on the one from Sim City 3000

The Sims 3: Seasons
Aliens and alien abduction return in The Sims 3: Seasons.

In The Sims 3: Seasons it is indeed possible for your Sim to abducted by aliens. The only way that it has happened (at least to me so far) is by visiting a graveyard during a full moon, or perhaps simply by walking around town. A Sim will gain a "investigating anomaly" action icon and then be abducted by aliens. A Sim will gain a negative moodlet from the abduction for 10 hours. Since it happened to my female Sim once, I do not know if your Sim can become pregnant from the encounter, but she did not get pregnant.

The Sims 2 Console
In The Sims 2 for consoles, alien abduction works as in Bustin' Out, except that abducted Sims will vomit and will yell at other Sims for no apparent reason. The Sim will not become pregnant or have a baby. One of the most popular methods of getting a Sim abducted is to make sure the Sim has high Logic and is in a good mood. Have the Sim gaze into the telescope for several hours, and at some time, he or she will be whisked away by a beam of light from the sky.

The Sims 2: Castaway
In The Sims 2: Castaway, there is an island named Crystal Island. On it, are giant green crystals and odd rock formations, and it is the only place in the game where a Sim may be abducted. For a Sim to be abducted, they must have the airplane radio and transmitter, two items used to call for rescue, and the radio must be placed on the island. The Sim must then place the transmitter and send an SOS. Upon doing so, an unseen UFO will suck the Sim into it and, to the player's delight, raise all motives to full. The Sim will then fall down, recollect itself, and yell at the sky, then run to a nearby sand gathering pit and vomit. The Sim will sometimes return with cans of Alien Food, but will not be impregnated or any other effects.

The Sims 2 Pets
In The Sims 2 Pets, Sims can be abducted if they use the telescope and stargaze. In an hour or so, the player will hear a strange noise, and see that the Sim is struggling to hold onto the telescope. The Sim will lose his/her grip and be sucked into an unseen UFO. A few hours later, the Sim will return with an information bubble which says that (NAME) has come back from his/her trip into the cosmos. Some players have reported that abducted Sims may bring items back with them.

The Sims 2 Nintendo DS
In the Nintendo DS version, you will be abducted if you walk out into the desert and wait for your sanity meter to hit zero. After the abduction, your Sim will appear in the manager's hotel room, lying on the floor. They will wake up after a few seconds. The Sim will find it very difficult to walk for the next few minutes. You can combat this by sleeping.

Trivia

 * In The Sims, If a Sim uses the telescope at the twilight hour between day and night (sunset and sunrise), the Sim will almost always be abducted by an unseen UFO.