GameNetworkingSockets vs Netcode for GameObjects

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.

Netcode for GameObjects is Unity’s high-level networking library for synchronizing GameObjects and world data during multiplayer sessions. Unity describes it as suited to games with smaller player counts and less complex game logic, including adding multiplayer to an existing GameObject-based single-player game. Networking can use client- or server-authoritative models. NetworkBehaviour components use NetworkVariables to synchronize state and RPCs to send messages over the network. Integrated scene management is enabled by default and synchronizes scenes across connected clients. Unity Transport is the default transport, while Unity Relay can provide Relay networking for GameObject and MonoBehaviour workflows. Unity Multiplayer Services sessions are compatible with the package, which handles gameplay state replication after players connect. The package is free, but installation requires an active Unity account with a valid license, a supported Unity version, and an existing project. Supported platforms listed include Windows, macOS, Linux, iOS, Android, XR platforms on those systems, most closed platforms, and WebGL with specified package versions. There is no matchmaking functionality; developers must use third-party services for matchmaking. A full client-side prediction and reconciliation system must also be built by the developer.