A certain block game
Multiplayer Framework for Node.js
#1 Open Source Unity Networking Library
Free and open source real-time strategy game
Accurate N64 Emulator
Highly compatible N64 emulator
Multiplayer at the speed of light
Flycast is a multiplatform Sega Dreamcast, Naomi, Naomi 2
Open-source Android/Desktop remake of Civ V
An open-source sandbox tower defense game
Build multiplayer web games played by millions
A lightweight, modular and versatile mod loader for Minecraft Bedrock
s&box is a modern game engine, built on Valve's Source 2
Minecraft map editor and mod
Dedicated Game Server Hosting and Scaling for Multiplayer Games
Multiplayer FPS game - Counter-Strike: Football
An open source reimplementation of the Among Us Server
Real Time Strategy game engine supporting early Westwood classics
High-performance, multiplayer code editor from the creators of Atom
Gradient Bang is an online multiplayer universe
YimMenu, a GTA V menu protecting against a wide ranges
Painless peer-to-peer WebRTC networking for rust wasm
Xash3D FWGS engine
Classic overhead run-and-gun game
You can make it - Open Source MMORPG Platform