You create a conversation with one or more people and can then launch apps into that conversation. The people on the other side didn't have to have the apps installed. If they liked an app, they can install it with one click and use it in their own conversations. If they wanted to change the app, they can do that too using the built in editor! All across a real-time encrypted p2p channel.
Despite how easy all these new P2P app frameworks are, none of them are as easy as Firestr was.
Example apps
https://github.com/mempko/firestr/tree/master/example_apps
Example p2p drawing application
https://github.com/mempko/firestr/blob/master/example_apps/d...
I've stopped developing it years ago. Maybe I should pick it up again if P2P is becoming interesting again for folks.