I ran a 12 player Spelljammer campaign that was house ruled heavily as my campaigns go. Spelljammer in brief is AD&D in Space with magically powered galleons shaped like fish and birds.
My house rule here was a system of 'Scrolls of Communication' between those ships wealthy enough to carry them. In essence the scrolls streamlined contact between the PC's vessel, a longship in the shape of a Hammerhead Shark or Hammership, and their home rock which had been built into a space port.
The scrolls enabled communication beyond visual range with flags. They were a convenience tool for me running the game. Elves may live hundreds of years, but wildspace travel will eat up more than enough of those just to deliver an invitation to dinner.
My players ran into a military ship that threatened them. They were out gunned and out run. So I left them to dabble about with how to get out of this one! I always love watching and listening to my players fuddle amongst ideas and arguments because they often come up with the most amazing solutions. And they not only succeeded here, they caught me pleasantly off guard.
They started drilling me on how the scrolls worked. Do they copy the text written and write it on the scrolls of the reciever? I decided that what was written on one scroll was whisked away and dimensionally transported to the recieving scroll.
And I wasnt really aware of the answer I had givin them until they proposed their solution.
They were going to polymorph some of the heavys and rogues into ink. Ink.
They then used the ink to write the destination which was the enemy ship and poured the rest onto the scroll.
And thus was born, Inky Doom. An infiltration through the com system.
They won the melees and a huge chunk of xp change for collaboration, and creativity.