The CMU KGB plays a delightful game called Capture The Flag With Stuff. This app displays game state information, just like the hardware timers we have built.
This app does not attempt to access traditionally private information (contacts, phone identity, file system, ...) nor does it access cameras, microphones, or other sensors of the device, except for the clock. It does, however, request access to the network status information of the device and, of course, access to the Internet. When connecting to the CMU KGB's CtFwS MQTT server, of course, the device's IP address may become visible to the CMU KGB's server, just as if it had visited the CMU KGB website. If the settings are changed to update which server the app attempts to use, that server will also, similarly, see the device's IP address.
Speaking of accessing websites, the application will, when requested by the MQTT server, grab a small file from a server-provided URL to update the handbook HTML it has cached. This may reveal the device's IP address to another server.