Streaming of the playing field (for the audience) - how?

I apologize for the general question, but:

I create a game, a kind of strategy, being played on a server in many game fields.
I need to add an audience option. Passive viewing of the playing field by the app for observers - not playing.

I have done the download, caching and preview of the map without any problem.
The map is modular and downloading a large map is only 2 bytes per square.
But ... the problem is with the NPC characters. Do you know "They Are Billions"? Well, now, in addition to players, I would like to give you the opportunity to preview what is happening on the map.

A smaller scale, but many (several hundred) NPC characters running on the map.
A lot of viewers. Architecture question-and-answer too quickly kills the link on the server.

I would like to stream information about these characters, and I do not know too much about streaming.

Could someone recommend me a link? Asset? Tell me something?

Best regards,
K.