GameNetworkingSockets vs Mirror Networking

GameNetworkingSockets is a free BSD-3-Clause transport library for games that sends reliable and unreliable messages over UDP. It handles messages larger than the underlying MTU through fragmentation and reassembly, with retransmission for reliable messages. Packets use AES-GCM-256, while Curve25519 supports key exchange and certificate signatures. Peer-to-peer connections can use Google WebRTC ICE for NAT traversal, with an option to plug in a signaling service. Multiple message lanes can share one connection under strict priorities or weighted bandwidth rules. Included diagnostics simulate packet latency and loss and measure detailed statistics. The library is written in C++ and also exposes a plain C interface; third-party bindings are listed for C#, Go, and Rust. Build instructions cover Linux, Windows, macOS, and iOS. Steam is not required for the open-source library, but authentication, signaling, and Steam Datagram Relay remain Steam-only services. Higher-level entity serialization, delta encoding, and compression are not included.

Mirror Networking is a free system for adding multiplayer capabilities to Unity games. It uses a server-authoritative model by default and supports dedicated servers as well as client hosts. Core tools include message handlers, serialization, distributed object management, and state synchronization. Unity components such as NetworkManager, NetworkIdentity, and NetworkBehaviour connect game objects and scripts, with automatic synchronization for transforms and script variables. Built-in transport choices include KCP UDP, Telepathy TCP, WebSockets, a multiplexer, latency simulation, encryption, and Edgegap Relay. Other transport connections include Steam, Epic Online Services, LiteNetLib, and ENet. Mirror is MIT licensed, with no paywalls or CCU costs. The maker says it stores no user data and performs no tracking, analytics, or advertising. Its feature list marks lag compensation and encryption as Beta, unreliable sync mode as in development, and bitpacking and prediction as being researched. The GitHub README recommends Unity 2019, 2020, 2021, 2022 LTS, or 6000.1 to get started.