The Irrlicht Engine is an open source high performance realtime 3D engine written and usable in C++. It is completely cross-platform, using D3D, OpenGL and its own software renderers.
The goal of this project is to produce a CAx-System for all people. Definition of CAx: en: http://en.wikipedia.org/wiki/CAx de: http://de.wikipedia.org/wiki/CAx
Intended to be a cross-platform 3D engine and toolkit using the Tao framework and allowing C#/F#/.NET developers to target Mac OS X and Windows with a single build.
Also includes accessory tools for managing builds and ports of your game product.