Minecraft is a sandbox video game created and designed by Swedish game designer Markus „Notch“ Persson, and later fully developed and published by Mojang. The creative and building aspects of Minecraft allow players to build with a variety of different cubes in a 3D procedurally generated world (Wiki).
Minecraft Club hosts Minecraft LAN parties and is a great place for kids to meet and play with each other and learn from the experts
Second Life is a free 3D virtual world where users can create, connect, and chat with others from around the world using voice and text.
Sansar is a platform for creating social VR experiences. It’s mission is to democratize VR as a creative medium, making it easy for people to create, share, and sell their own social VR experiences.
OpenSim ( OpenSimulator)
OpenSim is free, open source software that allows anyone to create a virtual world and run it on their own computer. It is fully decentralized, works in virtual reality mode with Oculus Rift, and allows avatars to teleport between worlds as easily as they follow links between websites.
Kitely provides OpenSim-based virtual worlds. You can visit existing virtual worlds for free, or create your own worlds for a very affordable price.
Inworldz is a place where you can express yourself and create your own paradise islands. Mingle and make new friends in this great Virtual World.
IMVU is a social entertainment community which allows you to create a 3D avatar, make friends, attend parties, customize your own room and doll, you can join IMVU for free or you can become a member which gets you coins to buy clothes, house furn…