aka ogre v2 - scene-oriented, flexible 3D C++ engine
3D Engine c++
Lightweight, high-performance HTML renderer for game developers
GLScene Engine for Delphi & C++Builder VCL Windows 32/64
A real-time 3D Engine written in Ada
GPU Raytracer from scratch in C++/CUDA
Vivid is a modern C++ 3D engine using OpenGL4+
A tool for creating models for the DelphiDoom Engine
Tao3D is a programming language for real-time interactive 3D
Vivid Engine 2 is an open source 3D Engine coded using C# and C++.
3D .NET engine for Windows, Linux, Mac
A public domain cross platform 3D game
Design and Display Happy Cube solutions
PHIGS (Programmer's Hierarchical Interactive Graphics System)
Webgl Engine
A cross-platform game framework based on OpenGL and GObject.