I would love a mod that allows for one to send local chat text message by typing a prefix in front of a message. This would allow for the creation of role play servers. Voice chat would be better, but perhaps what I am saying here could be modded in for the meantime.
I've been wanting a local/planet chat for a long time. Sometimes it's annoying or inappropriate for everyone to be spamming the same global chat channel. A mod is probably less likely. We probably have more chance of Eleon adding this themselves, although it may be a long time until they consider doing it.
The only thing that could be done would be a mod that distributes the messages in the faction chat, if prefixed, to all players on the same playfield. Would that be okay?
My CC mod (CommandCrate) features a 'private chat' like that by default, if you prefix it by 's! '.. It got whisper + reply + dnd (blocks whispers). You can tweak how it works if you desire (All CC commands are pretty much fully changable by yaml files) You could easily make one that sends to entire playfield aswell, if you want.
The API can handle private messages, faction messages and global messages... Downside is that all messages would show up in the chat window prefixed by "Server:" in red. Server say messages can be sent to a single player, a faction or to all. Alternatively, you could use the alert windows; blue, yellow with sound and red with sound. All three show in the top right of the screen for a specified time. Also, the pop up window can be used which may include up to two buttons. Or you can just wait a few more weeks, I'm bringing back my old mailbox mod... With a few extra features.