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
Write your game with TypeScript in UE or Unity
Self-hosted game stream host for Moonlight
s&box is a modern game engine, built on Valve's Source 2
The main repository for the Linux and Mac OS Bedrock edition Minecraft
Voxel game-creation platform with easy modding and game creation
Cross-platform 2D and 3D game engine with modular architecture
An Open Source Minecraft Launcher with Modern UX
Dedicated Game Server Hosting and Scaling for Multiplayer Games
Open source cross-platform multi-purpose game toolkit
An unofficial PC port of the Xbox 360 version of Sonic Unleashed
Pterodactyl® is a free, open-source game server management panel
Cross-Platform C++ 2D/3D game engine
HTML5 Phigros chart player/simulator
Emulator for the Game Boy, Game Boy Color, and Game Boy Advance
A bridge/proxy allowing you to connect to Minecraft
Mod manager for the video game RimWorld
Powerful, mature open-source cross-platform game engine for Python
Multi-platform Engine for Desktop, XBOX (UWP) and Mobile games
Lightweight console for Minecraft chat and automated scripts