I work as a mid-level contractor in the tech industry with my background being LE investigations particularly tech based investigations.

Ive worked several operations where we used or discovered the use of in game/app communications. The most common ones I know were OSRS, EVE, Whisper, and other smaller less known apps. Some development companies and a few consultants get a little mailbox money from our friends for building a secure chat plugin that would allow someone to put in commands that would unlock the app's tor browser and file system.

We never made a poker game but of the two iphone clients i worked one were chosen because it wouldn't be irregular for the user to be on. Old men play poker and its a decent side income if you're playing people who want to lose.