One framework for creating powerful cross-platform games
CTFs as you need them
Open Source MMORPG Framework
lua dev plugin for unreal engine 4 or 5
Arianne is an engine to develop multiplayer online games like Stendhal
JavaScript framework to build game engines, games, emulators and apps
Java Settlers
Mad Vandal's FortressCraft Mod Source Code
A synchronisation component for p5.js
2D game engine for traditional platform games
Single-/multi-player card game Mau Mau (similar to UNO®)
Java decentralized cross-platform network multiplayer game engine
Cross platform 2D/3D game engine written in C++11 & OpenGL ES 2/3
Educational framework for OpenGLES, OpenCL and OpenAL
C++ game libraries plus server.
TR Game Engine allows you to develop your game quickly and easily.
A multiplatform game engine for interactive fiction experiences
Open Source Virtual World and MMOG Development Platform
Cross-platform reimplementation of AMOS BASIC (runtime)
Fully fledged steam community SDK
Investigo - DX9 Performance and Debugging Toolkit