Steam Multiplayer Plugin
Personal Project
The Need This Code Fulfills
This multiplayer system is designed to simplify multiplayer session management in Unreal Engine. By leveraging delegates and a clean subsystem structure, it ensures scalability and flexibility for multiplayer games. Additionally the plugin is created in such a way that it can be used for a wide variety of games which use a client-hosting model.
Unreal Engine 5 Multiplayer Plugin
Online Multiplayer Subsystem
I built a multiplayer session subsystem designed to manage multiplayer sessions in Unreal Engine using the Online Subsystem, which can connect to services like Steam. It handles creating, finding, joining, and managing multiplayer sessions. When you create a session, the subsystem configures session settings (e.g., number of players, whether it's LAN or online) and attempts to host it via the Online Subsystem interface. For Steam, this involves broadcasting session data to Steam's matchmaking services so other players can find and join the game.
When finding sessions, the subsystem uses Steam’s networking features to connect the players. Delegates are heavily used throughout the process to track whether actions like creating or joining a session were successful, allowing the game to respond appropriately, for example, displaying a success message or retrying if a connection fails. This system uses a client-hosting model to allow for multiplayer gameplay without the use of dedicated servers.
Creating Game Sessions
Creating a session works by first checking if a session already exists and destroying it if necessary. Then, the subsystem sets up the session's rules, like the maximum number of players, whether it's a LAN or online match, and if players can join mid-game. These settings are passed to the Online Subsystem, which attempts to create the session on the chosen platform, like Steam. If successful, the session becomes visible to other players for matchmaking or joining.
Finding and Joining Game Sessions
Finding sessions involves sending a search request through the Online Subsystem to look for active game sessions that match certain criteria, like whether it's a LAN or online match. The subsystem collects search results, which are essentially a list of available game lobbies. If no results are found, the system notifies the player that no suitable matches were found.
Joining a session works by selecting one of those search results and telling the Online Subsystem to attempt a connection. The subsystem handles the technical details, like setting up the network connection and syncing the player's status with the host. If successful, the player is added to the chosen session, and the game continues from there.
Multiplayer Menu
This menu system interacts with the MultiplayerSessionsSubsystem to manage creating, finding, and joining multiplayer sessions. When the menu is set up, it assigns the MultiplayerSessionsSubsystem from the game instance and binds various events like session creation, finding, and joining. The Host button triggers a session creation request using the subsystem, while the Join button searches for available sessions. If a matching session is found, the system attempts to join it. The subsystem handles the complex networking logic, while this menu handles user interaction, visual elements, and transitioning between game states like the lobby or gameplay map.