Life state

Each expansion pack for The Sims 2 released added an alternate state in which Sims can exist. These states have unique triggering techniques, advantages and disadvantages. These states are:
 * Normal Sims
 * Ghosts (base game)
 * Aliens (base game)
 * Zombies (University, FreeTime, Apartment Life)
 * Vampires (Nightlife)
 * Servos (Open for Business)
 * Werewolves (Pets)
 * PlantSims (Seasons)
 * Bigfoot (Bon Voyage)
 * Genie (FreeTime)
 * Witches (Apartment Life)

Each life state offers new opportunities for the Sim, making certain aspects of play easier to handle and others harder.

However, most of the creatures listed above also appeared, in some form, in The Sims or its expansions. There are ghosts. While aliens are not seen, they are there, and may abduct Sims who use telescopes at night. In The Sims: Livin' Large, Sims using the chemistry set might make a purple potion that will temporarily turn a Sim into a monster.

In The Sims: Unleashed, Miss Lucille of Old Town sometimes ends up making a zombie when she tries to resurrect a dead Sim. The Genie and Servo were added in The Sims Livin' Large, and they look very similar to those that come with The Sims 2: Open for Business and The Sims 2: FreeTime, though Sims 1 Servos are objects and not playable Sims.

In a sense, werewolves, vampires, PlantSims and Bigfoots are added in The Sims: Makin' Magic. When a Sim makes the Beauty or Beast charm and then uses it, he/she can assume the appearance of these creatures. Of course, players may choose to treat this as a transformation or an illusion; the in-game effects are the same either way. The Sim who has been "charmed" is still a normal Sim, and gains no extra abilities or interactions. It could be said that witches and warlocks come with The Sims: Makin' Magic, but Sims who take up magic in Makin' Magic still look and act the same.

The Sims 3 and current EPs feature only 4 life states:
 * Sims
 * Ghosts
 * Mummies
 * Servos