Discord is great and we all love it. These guys outdid themselves again and created SDK for game-makers to implement their awesome technology within games. It's middleware worth considering not just because of great features it provides, but also because ... It's FREE! And best things in life come free. Should be easy to implement into UE4, it supports dynamic creation of channels so can work well for team chats, zone chats, guild chats (persistent, could also be joined outside the game). It offers both text chat (with it's many features) and low latency voice chat ... and on top of that it also supports bots (you know I love bots). Doesn't sound so bad does it? What you guys think?