Scenario
In The Sims 2, there are certain scenarios in the game for things. Scenarios have a timer and some sort of scoring system. They can be started in different ways. If your Sim passes the scenario, they usually get a positive memory and a couple wants fulfilled. Scenarios are also in The Sims 3 to a certain extent. The Sims 3 has opportunities, and the opportunities have a time limit and something positive happens if you complete them.
List of Scenarios
House Party
Wedding Party
Sports Party
Toga Party
Birthday Party
Graduation Party
Anniversary Party
Joining Private School
Dates/Outings
Joining Greek House
Opportunities (in The Sims 3, similar to scenarios in The Sims 2)