FishNet
An open Unity networking framework with spawning, RPCs, prediction, rollback, scene management, and multiple transports.
Why use it
Use FishNet to start with high-level components and add prediction for competitive or cooperative play.
Where it fits
Find engines, frameworks, code libraries, version control, and production automation.
What to check
The network model still needs design; hosting cost, cheat boundaries, and version compatibility are not automatic.