@Borat Sister,
You're welcome. I want to clarify, you want a game
where the kids will be inside on a computer... where they will have a simulation of being outside. Is this right?
If that is correct (rather than you wanting your kids to actually be outside with an app... which right now is not advisable) then Minecraft is a very good option that many kids ages 7-15 really like.
1. Minecraft can be used to play with kids from other families. My daughter joins a network with her friends. They are each in their own houses, but their onscreen characters interact with each other and work together. It is a great way for kids to "chill" (as my daughter puts it) with their friends.
2. Any computer simulation of "outside" is going to be artificial. That being said Minecraft presents a very compelling world to play in. It puts you in a world with raw materials; trees for wood, stone, animals, sand that you can then use to build pretty much anything you like, from houses to castles to electronic devices (yes, there are resources you can use to make circuits if you are so inclined).
3. The best part about Minecraft is that it encourages play. It is cooperative and creative.
If you are looking for something different, please clarify. I have raised three computer nerd kids (aged 15 - 28) I know pretty much every computer app that has been targeted at kids. Most of the other apps are centered around shooting people.