"Cross-media" developer Area/Code, maker of find products such as Drop7 and Parking Wars, just put out a new "massively single-player" browser-based game tie-in for Disney young adult novel series The Kingdom Keepers. Created by Ridley Pearson, the franchise follows a group of teens who serve as hologram hosts at Disney parks and battle against Disney villains called Overtakers.

Area/Code's Kingdom Keepers Online follows that plot, asking players to stop Maleficient and the Overtakers, who have escaped to the online world and are "infecting the virtual spine of the Internet". To combat the Overtakers, gamers choose from one of the series's five heroes to play as, enter the network using some futuristic device, and secure nodes scattered across the country.

Each node is a procedurally-generated level with Defense of the Ancients-style gameplay that has you leading a group of holograms against waves of enemies. After you've destroyed the enemy base, you can move to another web of stages connected to your current node (the different nodes have easy, medium, and hard difficulty ratings).

Though Kingdom Keepers Online is played as a single-player game, it's a collaborative experience in that online players are clearing a node multiple times to make them less infected, eventually driving the Overtakers out of the network entirely. As players disinfect the nodes, the Kingdom Keepers Online site is also unlocking video transmissions that add a bit of flavor to the universe.

You can play Kingdom Keepers Online for free and learn more about the books here.