Cocos simplifies game creation and distribution with Cocos Creator
scene-oriented, flexible 3D engine (C++, Python, C#, Java)
Multi-platform Engine for Desktop, XBOX (UWP) and Mobile games
Complete Open Source and Modular solution for MMO
Source code repository of the FreeOrion project
GLScene Engine for Delphi & C++Builder VCL Windows 32/64
... the open-source glide computer
TX Library is a tiny graphics library for Win32 written in C++.
Cross-platform real-time strategy game (3D)
2D Game Engine with Lua Scripting made on top of SFML
A Smarter Way to Tag FLAC, Vorbis, Lyrics, WMA, WavPack, and ID3 Tags
IL-2 Sturmovik 1946 Executable Memory Management Enhancer
scriptable game engine with built-in support for 2D graphics and sound
The Atomic Game Engine is a multi-platform 2D and 3D engine
Open-source, cross-platform, C++ game engine for creating 2D/3D games
An online multiplayer tactical warfare game for fast action combat!
2D Editor to manage garden or flat plan
Mad Science
Convert JPEG, GIF, PNG, BMP, PDF, TIFF, PICT and SGI to another format
a flexible game engine
An OpenSource (C# .NET) TeamPlay Environment.
a realtime graphics library
PixelLight is a cross-platform application framework