Roblox is a website that people of all ages create simple virtual lego blocks and build anything they like. They can range from a mini game party, a $hoot-out area, a hangout area for chats, etc.
The ideas are unlimited. You can also customize your character to look into anything you like. There's also a unique money system, so that you can buy your costume or places with. Enjoy!
Some words edited...
-mac