In Nightlife, each date is a challenge to keep both Sims as happy as possible while accumulating aspiration points.
It is also possible to import neighborhood terrains from Sim City 4.
The game contains some time-bound social challenges that provide a reward if successful.
A player will also need to make sure a Sim is happy and well by fulfilling wants (including lifetime wants, avoiding fears, and fulfilling motives).
Pregnancy, toddlers, teens, and elders are new stages of life.
All Sims age, and can live to 90 sim days depending on the degree to which their aspirations are fulfilled.
The Sims 2 builds on its predecessor by allowing Sims to age through six stages of life and incorporating a 3D graphics engine.
Babies, toddlers, children, teens, and adults can be advanced to their next life stage at any time during the 24 Sim hours before they will grow up automatically. Toddlers, children, teens, and adults can use the "Grow Up" self-interaction.
If the University expansion pack is installed, teens have the option to go to college, where they will be young adults for approximately 24 days. Players will need to build up talent badges, skills and relationships with other people, so that they can be successful in their career.
The player can choose between playing a pre-made inhabited lot, moving a household into an unoccupied pre-built lot, or constructing a building on an empty lot. The player switches among the "live" mode (default) to control Sims, the "buy" mode to add, move or delete furniture, or the "build" mode to rebuild the house.