Passing On

Passing On is an Android game in which teams of players compete against each other to be the first to pass on. Each team consists of two players with two different roles: Investigator and Ghost. One player helps the other to find the right location. One can talk to the other, but the other one can only communicate by knocking on his device.


  • Deliberate limitations in communication
  • Team competition mode
  • Multi-player game
  • Physical movement
  • Interaction between players
  • GPS-tracking between players
  • Real world physical artifacts
  • Lightweight

The Story

The story is about three restless ghosts who are living in Birlinghoven Castle. Each ghost has unique story which is written in paper beside devices. In addition, related to the stories there are lost memories for each ghost inside bottles located in different places. The bottles are separated from the ghosts by shape and name. Three investigators communicate with ghosts using mobile devices to help them. They have to find the correct location of the bottles to access the correct text. Through establishing a common language (as well as some trial and error) the ghosts guide the investigator to reach the specified location.

Playing the Game


To start the game players have to decide about their roles in the game. Once the roles have been selected, the Ghosts initiate the game by creating an instance and the Investigators join that session. Finally, the game starts after connecting to the server. It should be considered that neither the investigator nor the ghost know each other. This means, they will meet each other by solving last part of the game.

The Investigator has no interface on their mobile device. They talk to the ghost through a phone call established by the system. They receive "knocks" from the ghost in response-one knock for yes, two knocks for no, or perhaps one knock for left, one knock for right. The knocks should be even more obvious that there is no given language, and that they will have to invent that.

They follow the ghost's instructions, which lead them to a specific location. At that location an impressionistic haiku is in the bottle which is a part of the ghost's story. The investigator reads the text to the ghost over the phone. The ghost enters the correct order of key words then gives them directions to the next location.

The Ghost has a mobile device displaying a Google map with two points on it: one point represents the location of their Investigator, and the other shows the location of the memory site. They receive communication from the investigator through a phone call, but they can only respond by "knocking" via clicking a button on the interface. When the investigator reads them the text, they click on the "Memories" tab where they must enter in a three-number combination to solve the memory, and move to the next one.

Once three memories have been solved in this fashion, the investigator and ghost alike are directed to meet at a single location, where the player guides the ghost through the portal so that they can pass on.


Passing On uses the ZebroGamQ protocol developed by TOTEM to manage the game session, take care of sending GPS and knock patterns between teammates, and keep the game state synchronized across teams.

TOTEM Designer has been used to easily create assets and parse them into the program after exporting to XML, and TOTEM Scout to precisely tie assets to a location in the field using a smart phone.

Walkie Talkies were used to make voice connection from investigator to ghost. 


The Passing On game was created by Jacob Garbe, Marta Clavero Jiménez, Jon Back, and Sahar Vahdati during summer school “TOTEM Mobile Mixed Reality Game Jam Hackathon” in 2012 at Fraunhofer FIT.