Multiplayer Overview

There are two kinds of users for the Networking feature:

• Users making a Multiplayer game with Unity. These users should start with the NetworkManager or the High Level APIA system for building multiplayer capabilities for Unity games. It is built on top of the lower level transport real-time communication layer, and handles many of the common tasks that are required for multiplayer games. More info
  See in Glossary.
• Users building network infrastructure or advanced multiplayer games. These users should start with the NetworkTransport API.

High level scripting API

Unity’s networking has a “high-level” scripting API (which we’ll refer to as the HLAPI). Using this means you get access to commands which cover most of the common requirements for multiuser games without needing to worry about the “lower level” implementation details. The HLAPI allows you to:

• Control the networked state of the game using a “Network ManagerA Networking component that manages the network state of a Project. More info
  See in Glossary”.
• Operate “client hosted” games, where the host is also a player client.
• Serialize data using a general-purpose serializer.
• Send and receive network messages.
• Send networked commands from clients to servers.
• Make remote procedure calls (RPCs) from servers to clients.
• Send networked events from servers to clients.

Engine and Editor integration

Unity’s networking is integrated into the engine and the editor, allowing you to work with components and visual aids to build your multiplayer game. It provides:

• A NetworkIdentityA Networking component that allows you to assign an identity to your GameObject for the network to recognize it as a Local Player GameObject or a Server Only GameObject. More info
  See in Glossary component for networked objects.
• A NetworkBehaviour for networked scriptsA piece of code that allows you to create your own Components, trigger game events, modify Component properties over time and respond to user input in any way you like. More info
  See in Glossary.
• Configurable automatic synchronization of object transforms.
• Automatic synchronization of script variables.
• Support for placing networked objects in Unity scenesA Scene contains the environments and menus of your game. Think of each unique Scene file as a unique level. In each Scene, you place your environments, obstacles, and decorations, essentially designing and building your game in pieces. More info
  See in Glossary.
• Network components

Internet Services

Unity offers Internet Services to support your game throughout production and release, which includes:

• Matchmaking service
• Create matches and advertise matches.
• List available matches and join matches.
• Relay server
• Game-play over internet with no dedicated server.
• Routing of messages for participants of matches.

NetworkTransport real-time transport layer

We include a Real-Time Transport Layer that offers:

• Optimized UDP based protocol.
• Multi-channel design to avoid head-of-line blocking issues
• Support for a variety of levels of Quality of Service (QoS) per channel.
• Flexible network topology that supports peer-to-peer or client-server architectures.

Authentication

Unity’s networking implements simple built-in authentication features which provide basic support for validating sessions, but is not a robust authentication solution.

Robust authentication can be an important factor in developing a multiplayer project, as it helps to prevent malicious users from hijacking player sessions, impersonating other users, disconnecting legitimate players from games, or other malicious actions specific to your game or app.

Because Unity only provides simple built-in authentication, if you require robust protection against malicious actions in your game or app, you should use 3rd party authentication and encryption solutions, or implement them yourself using plugins such as this reference implementation and the NetworkTransport API.

Sample Projects

You can also dig into our multiplayer sample projects to see how these features are used together. The following sample projects can be found within this Unity Forum post:

• Multiplayer 2D Tanks example game
• Multiplayer Invaders game with Matchmaking
• Multiplayer 2D space shooter with Matchmaking
• Minimal Multiplayer project