scene-oriented, flexible 3D engine (C++, Python, C#, Java)
Voxel game engine in C++ with OpenGL
Open 3D Engine (O3DE) is an Apache 2.0-licensed multi-platform 3D
Multi Theft Auto is a game engine
Orx: Portable Game Engine
RTSish Game Engine
C++ lightweight cross-platform game engine
Spring is a free RTS engine developed for Windows, Linux and Mac OS X.
Vivid is a modern C++ 3D engine using OpenGL4+
A fast, scalable, distributed game server engine/framework for C++
A 2D game engine and level editor
Real-time RPG for PC/tablet/phone; multiple quests and random dungeons
Intrinsic is a Vulkan based cross-platform game and rendering engine
A runtime-programmable, cross platform, game engine
Small OpenGL based game enegine
A retro style video game engine for RPGs and adventure games.
Tactical, turn-based game engine, that uses OpenGL and WinAPI
WIP Game engine
A DirectX based graphics/physics engine