You can make it - Open Source MMORPG Platform
The flexible game engine
A Minecraft Launcher which is multi-functional, cross-platform
Godot is a powerful cross-platform game engine
Solar2D Game Engine main repository (ex Corona SDK)
A complete 3-D game development suite written in Java
s&box is a modern game engine, built on Valve's Source 2
Self-hosted game stream host for Moonlight
The main repository for the Linux and Mac OS Bedrock edition Minecraft
Write your game with TypeScript in UE or Unity
Cross-platform 2D and 3D game engine with modular architecture
Powerful, mature open-source cross-platform game engine for Python
A Minecraft Java Edition Launcher for Android and iOS
Voxel game-creation platform with easy modding and game creation
Pterodactyl® is a free, open-source game server management panel
Open source cross-platform multi-purpose game toolkit
Atmosphère is a work-in-progress customized firmware for the Nintendo
Lutris desktop client in Python
Cross-Platform C++ 2D/3D game engine
An Open Source Minecraft Launcher with Modern UX
Emulator for the Game Boy, Game Boy Color, and Game Boy Advance
Multi-platform Engine for Desktop, XBOX (UWP) and Mobile games
V1, Mirror Classic. V2, Mirror Engine: Join Discord for access
Open Source MMORPG Framework
Cocos simplifies game creation and distribution with Cocos Creator