Revised May 1, 2019.
The second major release of Zephyr was originally intended to be a cloud-based solution in which the Zephyr desktop and Android clients would connect to and communicate with each other via an online server. A user's Steam account would be used for authentication and developers could register their own apps to utilize the Zephyr infrastructure.
Project Tempest was largely successful, but concerns regarding privacy, security, cost, etc. eventually led to the abandonment of the effort.
The following repos were associated with Project Tempest are archived: