What gives you a "warm feeling" inside when playing?

For Sims 1, definitely the soundtrack and the random whistling Sims do as they pass by.

For Sims 3, even though I loved it, I don't remember it making me feel "warm".

For Sims 4, the first thing that pops into my head is the seasons, especially fall. I love fall in Sims 4; the sky is so wonderfully gloomy, and the crows cawing in the background make me shiver in a good way. Add a cozy fire and the family dog dozing on the rug, and you've got a perfect picture.