I'm not sure if your parents would agree, but you should try the GTA series.
To me, it seems that you don't have to finish the game or anything to have fun, because if you unlock all of the city, the possibilities of role play are very vast. For example, you can drive emergency vehicles, or drive taxis, or work somewhere.
If you've not played Half-life 2 yet, I really recommend it. I'm terrible, but it's so much fun. It's a valve title, like the Portal games and Team Fortress (also very fun). Honestly, so cool.