This project is about creating a game to build and install temperature and humidity sensor checkpoints and retrieve data from them regularly. The game has only 2 teams: the engagers vs. the resilients. The hardware is open and relatively easy and cheap to build. The game play encourages regularity to get teams to retrieve data often, initiative to get teams to add their own sensor checkpoints, collaboration and fun to get many players involved and interested in the data they gather.

This project is solving the Cool it! challenge.


Why this project

Our objectives with this project is to solve the Cool-it challenge in an engaging way with people. We believe that by involving people as a team in playing, they will have more interest in the data they collect and more awareness about what it actually means in terms of climate issues such as the heat island effect. Even the setup of the game is open to participation, as players can contribute to the game by adding sensor kits.

We want to have players motivated in taking part for the fun, the learning experience and the social meaning it provides. All of it with a sense of belonging to a community of players who share the same expectations. To that end, we came up with a mix of game-play design, hardware and software.

Game-play design

The winning team is the team that has the highest score. To win points for their team, players can check-in at sensor checkpoints or build and register new checkpoints. Each sensor checkpoint has a flag and a pool of available points.

The detailed scoring mechanism is available on the project website.

Pool of points

When checking-in, players get the number of points available in the pool. If the players’ team has the sensor checkpoint’s flag, then they score double points. The number of points available in the pool correspond to the richness of the data available at the sensor checkpoint. The sensor checkpoint will log data every hour and will not save more than 24h of data. When checking in, players will retrieve data and send to server.


In order to capture the flag of a checkpoint, teams need to send many players to check-in and get valid points more regularly than the opponent team.

New checkpoints

To activate a new checkpoint, teams must complete a registration process:

  • hardcode the location on checkpoint (will be used to cress-check location data)
  • send data over a first time (to cross-check location data the first time)
  • send a picture of the device (to display on map)

The game organizer check the location accuracy and also that this checkpoint is not too close to another (less than 100m)


For the sensor checkpoint part, we use open hardware. The detailed instructable to build it has been made available on the project website . The required components are (price in usd):

  • Arduino Nano $6.96
  • HC-06 bluetooth board $6.99
  • DHT22 temperature and humidity sensor $4.29
  • Solar panel $9.55
  • DC-DC Step Up Boost Module $2.84
  • Charge board $0.99
  • 18650 batteries $4.79
  • Case + cable $3

The actual cost of the device is roughly $40. This is a non-optimized cost yet.


The Android app is native code. The webapp is a standard PHP application, using mySQL database. When checking-in the smartphone also sends its longitude and latitude, so that the server can cross-check with the hardcoded location of the checkpoint.

Note: the application is only at prototype stage and is not fully secured yet.


Maintenance of hardware

We believe that because the hardware belongs to the teams, the players already have a good incentive to take care of it. We could also imagine to adapt the gameplay to encourage more this behavior, by for example assigning special missions. To reduce risks towards non-players, sensor checkpoints can be located in managed communal outdoor spaces, for example restaurants, companies, gardens, etc.

Upgrade with more sensors

The system could be thought to collect not only humidity or temperature data, but also air pollution, light, etc. As long as we provide an open design and incentives for teams to take a checkpoint and upgrade it, then thanks to the game, we could get even more valuable data about the environment and raise interest and awareness of players towards it.

More data with more memory

The current hardware design use the memory available by default on the arduino board. This much restricts the data that can be saved, before a player come to check it in. To overcome this limitation, we can integrate an SD card in the module.

Project Information

License: Common Development and Distribution License 1.0 (CDDL-1.0)

Source Code/Project URL:



  • Le Duy
  • Hoang Le
  • Hai Nguyen
  • Hoanh-Anh Phan
  • Nhan Nguyen