Second Life
Some people use this multi-user virtual environment (MUVE) for entertainment purposes, though it is not a game because it does not have any single goal that players must achieve. Other people use it to work or to study. Anyone is free to do anything they want, as long as they respect the Terms of Service. They are also free to create new things and add them to the virtual world. Players can make a lot of different things, including buildings, clothes, and landscapes. This is why Second Life is considered a platform, too.