mul83rry 

A free package for creating online multiplayer games, using tcp protocol. includes client-side(Unity) code and some other utilities to help online game developing faster. see more in http://tcpserverkit.com

Jaguar is a free powerful package for creating online multiplayer games using UDP protocol which supports reliable messages and big messages powerful matchmaking room system and more

A package for creating online multiplayer games, using tcp protocol. work with https://www.nuget.org/packages/TcpServerKit server for more detail see in https://github.com/mul83rry/TcpServerKit