Playing with "communication outside the game" rules

[Gamma Emerald]

I'm sort of interested in running a game or a series of games that messes around with the "no outside communication" rule, and I'm trying to figure out just what kind of changes I can make that will actually lead to interesting play. I'd love to get some ideas here and maybe some links to other games that have modified this rule with interesting results.

The two things I definitely don't want to mess with are

• no communicating once you're dead, and
  
• no communicating with non-players or where non-players can see.

Beyond those I'm wide open to possibilities.

As one example: for those of you who don't play Town of Salem, there is a means in that game to "whisper" to other (living) players during the day. Everyone is informed that Player A whispered to Player B, but not what was said. This seems like something that could be interesting here,

except

that I have no idea how to implement it... the only means I can think of would be to give every pair of players a PT and make an announcement in-thread whenever they use it, which sounds pretty extreme and ridiculous (a 13p game would require 78 PTs). Any better ideas than this?

Firebringer ran a Watch Dogs game with this mechanic where you PMed you message to the mod and they sent it