The Chat UI & Speech Bubbles system pack provides the base means for easily adding a MMO-style in-game communications system (a scrolling rich-text chat box with support for many commands, and a speech bubbles system) to your game. The pack, which is designed for the new Unity UI (UGUI) focuses on providing the user interface and interaction components, and does so in a thoroughly-documented and extensible way, so that you can easily integrate it with your particular framework.
The behavior and look of the components can be modified easily, most of the time through the unity editor itself. Also, the full source code is provided, so that you can check how everything works and modify or extend it as you see fit.
This package does not provide (and it is not intended to) the actual backend system for your chat. That is, it does not provide the chat channels, group channels or private messaging systems. It is designed to provide the user interface for those, which are most often very specific to the game.