Moon Tower Defense

2019 Critical Northwest art festival project

Remote fire effect tower in river – the main reason we went for wireless communications.


Imagine sitting atop a tower in an inviting swivel turret with firehose style water cannon pointed out across the river waiting to soak river riders at the push of a button on at hot July afternoon. But wait… whats wrong? No pressure? Better bring some friends to bring the dance vibes and activate the cannon.

But by night it’s too dark to aim. So the LEDs come on, the fire towers come alive and the night fills with flickering, dancing shadows.

Design challenge

Actuators and sensors are located in a river or atop a tower. Their code needs to be simple and rarely changed. One master “brains” controller is kept easily accessible and can be reprogrammed frequently.

Additionally cabling needs to be minimized somehow as distances are considerable. So we went with WiFi for our communication network to avoid long Ethernet or other cable runs.

Technical details

  • IoT technology, though we don’t have it actually hooked up to the internet
  • MQTT for communication
  • ESP8266 for each sensor or actuator. Many cheap processors handling individual tasks
  • 802.11 WiFi for network
  • C++ with the Arduino IDE


  • one is the brains listening to all the inputs and issuing output commands
  • some are simple sensors like a button and simply transmit their state
  • others are effects controllers and respond with light or fire to animation commands from the brains
  • several are motion sensors that detect people