Online Multiplayer Extension for GDevelop

This extension is designed for beginners creating online games. If you want to build more advanced online games, consider using the existing multiplayer features or extensions (such as WebSocket Client, Firebase, or P2P).

⚠️ This extension is experimental and not really practical yet. Development might also stop at any time.
⚠️ This extension isn’t a good fit for action games that need precise synchronization.
⚠️ This extension won’t work if the server is down.
⚠️ The server might be restarted at any time without notice for development.
⚠️ Running your own server isn’t supported.
☕ I’d really appreciate your support to help keep this server running.

🤔 How is this different from GDevelop’s official multiplayer?

This extension:

• Has no limit on the number of players (more than 8 is possible).
• Lets you choose which data to sync (so it’s clear what is being synchronized).
• Uses a fixed communication interval of 0.1 seconds.
• Allows you to save data on the server (SSV feature).

📖 How to use

Import the downloaded "OnlineMultiplayer0.0.0.json" file into your project.

There is no manual at this time. Please refer to the following video.

ℹ️ An object with the online player behavior can only exist in one place on the stage. For example, if you want to share bullets fired by a player, you must use a shared string.
(It’s more efficient to share the shot’s timing and angle once, rather than constantly sharing the bullet’s position.)
(This extension is not designed for exact synchronization.)

Deleting an object with the online player behavior will automatically disconnect it from the server.

⚠️ If the game window is completely hidden behind other windows or minimized, the game will pause, and that player will be disconnected after 5 seconds.

🪄 About how it works

A room is automatically created in the server for each scene in each game.

Information such as the position of player characters connected to the same scene is shared.

It uses WebSocket for communication.

📬About shared string

Each online player can share an individual string. This is useful for chat and JSON sharing.
See "Chat example" or "Shot example" for details.

🌅 About Server Scene Variables

For each scene, you can store one array with up to 10 children on the server.

To use this feature, declare a scene variable named “SSV” as an array in the Variables Editor. SSV stands for Server Scene Variable. (Make sure to use uppercase letters.) The SSV array can contain up to 10 numeric children.

While connected to the server, the SSV is automatically updated. Do not modify its values directly.

SSV is preserved even if the server is restarted.

SSV can be used even in scenes where the "Online Player" behavior does not exist.

For more details on how to use it, check out the descriptions of the “Connect to variable server” action and the “Modify Server Variable” action.

🃏 About the Host

This feature makes it easy to manage the flow of the game.

The server always designates one player as the host. Usually, the player who has been connected the longest is chosen as the host.

For details on how to use it, see the “Host and SSV example”.

🚫 Limitations

This extension has the following limitations to protect shared servers:

• Communication at 0.1 second intervals.
• The shared string must be within 1000 characters.
• javascript obfuscation.
• The server restarts at a scheduled time every day. At that time, all connections will be disconnected.

📂 Example project file

"OnlineMultiplayerExtensionExample0.0.0.zip" is the example project file. Open "game.json" in GDevelop.

List of examples included in the project file.

• Basic example
• Chat example
• Random example
• Shot example
• Host example (Old)
• User name example
• Host and SSV example

👾 Games created with this extension

Bomb Poi Poi

Colosseum of Thieves

🐛 Probably fixed.
This extension may not work on Android apps.

ℹ️ The fix was on the server side. Please make sure this extension works with your android app. 👍

I have confirmed that WebSocket communication from GDevelop works on Android 7, but not on Android 11. (If on browser, it also works on Android 11) Therefore, this extension will not work on Android 11. (⚠️ The exact version of Android that doesn't work is unknown)
This issue is likely to take some time to resolve.