Sims moving out of town

[Merlon]

While I was playing the game, my neighbor moved out from the city, and I was wondering how is it possible?

I only have TS3, no DLCs, no expansion packs.

So the question is, is it really possible to move out from the city without DLCs/expansion packs?

[Dobroski]

I assume you have Story Progression on. If you do have it on (you can check in the options menu), then Sims naturally leave town/die so new Sims can live in the town.

[marstinson]

Assuming that you do not have the Story Progression mod from NRaas installed (nrass.wikispaces.com), then it's EA's story progression at work. If you have Story Progression installed, then it's Story Progression since it turns off EA's and substitutes its own functions.

Without installing other playable worlds your Sim cannot do this. If you have other worlds installed, you can move your household to those other worlds. It's under Real Estate on your smartphone or any computer and it kind of combines the "Move" real estate function with starting a new game as it sells your house and contents and gives you the money as starting funds in the new world. The Traveler mod from NRaas adds a lot more flexibility to the process along with the option of just taking a vacation in those worlds and returning to your home world at the end of the vacation (World Adventures is required for this).

Back to the Sim leaving question, when the town's population gets high enough, Sims will sometimes (not sure what the algorithm behind it is) autonomously "emigrate" to another town. They don't actually move, but are just kind of removed from the game.

I don't recall whether foreign Sims were part of the base game or introduced with World Adventures, but if your Sim had a relationship with them, they should remain on the relationship panel as a foreign Sim, so you can chat long distance, invite them for a visit, and that kind of thing. They may occasionally show up as tourists (again, possibly a WA function). Tourists are essentially homeless Sims who hang around for anywhere from a few Sim-hours to a couple of Sim-days before literally disappearing, only to randomly reappear some time down the road.