GameNetworkingSockets vs Photon Fusion

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.

Photon Fusion is a state-transfer netcode SDK for multiplayer games made with Unity, Unreal, and Godot. Its tick-based simulation supports client-side prediction and snapshot interpolation, while lag compensation addresses the delay between a client firing and the server registering a possible hit. Developers can choose full-consistency replication or eventual-consistency replication, which uses less bandwidth per object. Available network topologies include dedicated server, client host, and shared authority. Engine availability has qualifications: the product page lists all three engines, while documentation marks Unreal as early access and says Godot early access is available by contacting Photon. Dedicated-server use is described as a headless Unity build and requires third-party server orchestration at additional cost. Free plans include a 100-CCU option and a development-only option for 20 concurrent users. A one-time 100-CCU plan costs 95.00 USD for 12 months; monthly plans include 125.00 USD for 500 CCU. Premium Cloud is billed at 0.50 USD per CCU per month, with a 1,000 USD monthly minimum. All plans include online documentation, samples, tutorials, video streams, and help with account, billing, and service-status issues.