LuraNetworking is plugin for unity to create multiplayer games easily, It uses UDP protocol which is fastest multiplayer solution, It has support of unlimited clients, and comes with it's full source code, which can be modified on both client & server side, source code is included.
LN API is super-simple, and it has low learning curve & notification based system for scripts.
Documentation and demos are included with package, they'll make it easier to give you an example how to use it.
Features:
Cross-Platform
Easy to uses
Open-Source
Integrated components
Well documented
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