Base Defense


Designing a Ball-Throwing Game Installation

Aug 2016


Base Defense is a large-format multiplayer game controlled by throwing motion-tracked balls at a screen. Base Defense uses stereo IR cameras to track retroreflective balls and detect hits against a planar surface. It’s kind of like a big golf simulator.

Motion-Controlled Cooperative Play

Built by Anticlockwise Arts, the game is a wave shooter combined with elements from tower defense. Participants work together to protect the base from wave after wave of enemies. By throwing balls at the screen, each player destroys enemies before they reach the base. Power-ups randomly appear and, if collected, upgrade the weaponry for all participants.


Retroreflective Balls

Each ball was handmade using retroreflective material.


Fun, Large-Format Game

Each participant helps the others in a massive cooperative play experience.


Lots of User-Testing

Base Defense underwent lots of user testing with graybox levels before adding final graphics and polish.

The Process

Base Defense was an evolution of an early experiment created at Anticlockwise by Cory Barr called Shatterwall.

The project was a well-distributed collaboration. Cory came up with the initial “shatter wall” prototype. Paul came up with the final IR tracking solution. Rich developed the ideal portable hardware rig. And, Liz designed all the art assets. I designed the game and the underlying client / server architecture.

For the game, I wanted to make sure that everyone was encouraged to work together and that they felt a sense of group accomplishment. For this reason, there is no action that can hurt the group’s performance. Actions can only be benign or helpful. In this way, everyone is encouraged to participate and succeed as a group.

Base Defense has a tracking layer written in C++ using OpenFrameworks and a presentation layer developed in Unity.

Keywords: Interactive Installation, Infrared Tracking, Multiplayer Game, Unity, OpenFrameworks

Matt Sonic