Castle Infinity is a discontinued Massively multiplayer online game, the first intended for children. It was launched by Starwave Corporation in 1996, and features personalized avatars, an embedded message system and live chat in a 2D side scrolling game world. It survives as a freeware MMOG.

The game is full of interactions that force players to collaborate with each other in order to pass from one area to the next, by way of four-person vehicles and other game-like lobbying devices.

The a cappella group The Bobs provided several original songs for the soundtrack. Additionally, members of the band also lent their voices for most of the characters.