A certain block game
#1 Open Source Unity Networking Library
Free and open source real-time strategy game
Highly compatible N64 emulator
Dedicated Game Server Hosting and Scaling for Multiplayer Games
Multiplayer Framework for Node.js
Gradient Bang is an online multiplayer universe
Accurate N64 Emulator
Flycast is a multiplatform Sega Dreamcast, Naomi, Naomi 2
Painless peer-to-peer WebRTC networking for rust wasm
Open-source Android/Desktop remake of Civ V
An open-source sandbox tower defense game
Multiplayer at the speed of light
A lightweight, modular and versatile mod loader for Minecraft Bedrock
You can make it - Open Source MMORPG Platform
Minecraft map editor and mod
Xash3D FWGS engine
s&box is a modern game engine, built on Valve's Source 2
Voxel game-creation platform with easy modding and game creation
Real Time Strategy game engine supporting early Westwood classics
An open source reimplementation of the Among Us Server
Classic overhead run-and-gun game
An unofficial rules engine for the world's greatest card game
Magic Another Game Engine
Multiplayer FPS game - Counter-Strike: Football