Story progression

Story Progression is a very useful, but unpredictable option in The Sims 3, and is a much more powerful version of free will. It helps keep a town alive and balanced. With Story Progression, uncontrolled Sims' lives progress normally: Neighbors may move away, new ones will move in, get promotions, get married, have children, make enemies, and even die. In this way, it adds a true sense of realism to the game, enhancing the gameplay experience in incredible, surprising ways. Sam Player had confirmed in an interview with GameSpot that the console version of The Sims 3 will have the story progression feature.

Although it is seen by some as efficient and clever (and the game recommends that it be enabled) story progression can sometimes cause unwanted and at times highly chaotic events to occur in the player's utopia, as it is very random in what it decides; the player may return to their other households to find their families in many sudden situations that they may find difficult to reverse. Story progression may result in unwanted marriages/divorces, absurd relationship changes (such as best friends becoming rivals), new members to the household or members that have curiously moved away, job losses, etc. As the game recommends that story progression should be enabled, many players uncertain of it have fallen victim to it and have become frustrated with its occasional disastrous effects. Strictly speaking, story progression should only be enabled if the player is fully sure that they do not mind inactive Sims running their own lives and making their own choices, even if it may inadvertently result in hard work gone to waste.

Effects

 * Sims grow older with the player's Sims, letting them keep childhood friendships.
 * Sims will sometimes have babies through adoption or with another Sim.
 * Sims in any inactive/uncontrolled households can be moved out.
 * Sims in inactive/uncontrolled households can switch jobs or get fired.
 * Uncontrolled Sims do not complete wishes.
 * Switching to a new household will let others to loose their wishes.
 * Sims will eventually die and their graves will be accessible via the mausoleum in the graveyard by clicking the option 'Manage The Dead"
 * Sims will sometimes get married, though it's very rare.
 * Sims may become friends, rivals, enemies, or love interests.
 * Sims may Go Steady.
 * Sims may get divorced.
 * Sims may change weight.