GLScene
- Delphi OpenGL engine including visual components and objects for rendering 3D scenes.
- http://glscene.sourceforge.net/

Titan Project
- A game engine using OpenGL that is able to render Quake3 maps and supports most Quake3 features. [Modified BSD license]
- http://castano.ludicon.com/oldies.php

Crystal Space
- Free (LGPL) and portable 3D Game Development Kit written in C++, OpenGL and software renderer.
- http://www.crystalspace3d.org/main/Main_Page

AgentFX
- 3D engine for games and high-end 3D applicationb based on Java and using OpenGL API. Free and commercial versions.
- http://www.agency9.se/products/agentfx/

3D Engines Database
- Overview of 3D engines for games, business applications and virtual reality with various platforms, APIs and programming languages.
- http://www.devmaster.net/engines/

Bonzai Software
- 3D game engine based on the OpenGL API written in C++. Also real-time computer graphics examples using the OpenGL API.
- http://www.bonzaisoftware.com

The Nebula Device 2
- Realtime 3D game/visualization engine, written in C++, scriptable through Tcl/Tk, Python and Lua. Supports D3D and OpenGL for rendering, runs under Linux and Windows.
- http://nebuladevice.cubik.org/

APOCALYX Engine
- OpenGL 3D engine with GPL license, 3D, Physics & AI
- http://apocalyx.sourceforge.net/

ExoEngine
- C# OpenGL and Cg 3D Game Engine for .NET
- http://www.exocortex.org/3dengine

OGRE
- C++ Object-oriented Graphics Rendering Engine.
- http://www.ogre3d.org/

Universe Generator System
- Full featured, object oriented and multiplatform 3D engine.
- http://ugs3d.sourceforge.net/