Xivio.com was a commercial children's virtual world website created in 2006 by Gavin Conrad. This is the legacy World Server Java Core made available to the world to do with as it wishes.
Math game where up to 4 students can play online against each other. By moving their figurines around a colorful pseudo 3D board, players answer math questions and can play tricks against their opponents. Client and server distributed under Affero GPL 1.