Content pack

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Expansion packs (EP) are a kind of add-ons for games. They make the original game more interesting by providing new things to the game, and are often centered around a theme. They require the original game (also known as base game) to work. Sometimes, collections or compilations of the base game and one or more expansion(s) are released. The Sims 2 and The Sims 3 also offered mini-expansions called stuff packs (SP), which offered only new objects and clothes, but no gameplay changes. Gamers are advised to check what an edition includes before buying it.

Themes
Between The Sims 1, 2, and 3, there have been 17 expansion packs released total (not including stuff packs) - between those packs, some themes have been used more than once, some have only been used once, and some have been incorporated into the base game. Some major themes are:
 * Pets: Pets are introduced in The Sims: Unleashed and reintroduced in The Sims 2: Pets. All versions of The Sims have had aquariums, fish that require a minimum of maintenance, although The Sims 3 and The Sims 3: World Adventures allow the keeping of bugs, butterflies, snakes, frogs, snails and crocodiles, as well as fish.
 * Dating: Dating was added with The Sims: Hot Date and reintroduced with The Sims 2: Nightlife. Dating is included in The Sims 3, though it is simplified from The Sims and The Sims 2.
 * Gardening: Gardening was added in The Sims: Unleashed and brought back in The Sims 2: Seasons. Planting seeds and other gardening activities are included in The Sims 3.
 * Vacations: Vacationing was added with The Sims: Vacation, then again with The Sims 2: Bon Voyage, and a similar "travel and adventure-type" theme is the basis of The Sims 3: World Adventures, the first expansion pack for The Sims 3 .
 * Adventure: Adventure was added in The Sims 3. Collecting gems, butterflies, and metals was incorporated into the base game. Adventure was also seen in The Sims 3: World Adventures, as Sims can go to France, China, and Egypt to discover and adventure.
 * Magic: Magic was the centerpiece of the final The Sims expansion pack; The Sims: Makin' Magic as well as the final planned The Sims 2 expansion, The Sims 2: Apartment Life. Magic was left out of The Sims 3 base game, although it may appear in a future expansion pack.
 * Cars: Personal car ownership was introduced in The Sims 2: Nightlife and was incorporated into The Sims 3 base game. In The Sims 3: Fast Lane Stuff, new cars will be available
 * Fame: Being famous was the main theme of The Sims: Superstar. Fame was not incorporated into The Sims 2 series at all, though Sims can have reputations with The Sims 2: Apartment Life. Fame is found to a lesser degree in The Sims 3 but is a major feature of The Sims 3: Late Night.
 * College Life: Central theme of The Sims 2: University, but left out of The Sims 3.
 * Weather: Main theme of The Sims 2: Seasons, but left out of The Sims 3.
 * Businesses: The idea of Sims managing their own businesses was central to The Sims 2: Open for Business, and was included in The Sims 3, though business ownership was simplified and businesses could not be founded independently or formed on private lots. It also seems to be a part of The Sims 3: Ambitions.
 * Apartments: Created in The Sims 2: Apartment Life, but left out of The Sims 3.
 * Parties: Parties, while always possible to some extent, were the main theme of The Sims: House Party and were included in The Sims 2 and The Sims 3 base games.
 * Hobbies: Hobbies was a theme in The Sims 2: FreeTime, but appears to be in The Sims 3: Ambitions.
 * High End Living: High End Living was always possible, and expansion packs would frequently add some high-end objects. It was also a theme, though perhaps not a major theme, of The Sims: Livin' Large. It was also a theme of The Sims 2: Glamour Life Stuff, (arguably) The Sims 2: Mansion & Garden Stuff, and The Sims 3: High-End Loft Stuff.