The Irrlicht Engine is an open source high performance realtime 3D engine written and usable in C++ and also available for .NET languages. It is completely cross-platform, using D3D, OpenGL and its own software renderer, and has all of the state-of-the-art features which can be found in commercial 3d engines. We've got a huge active community, and there are lots of projects in development that use the engine.
You can find enhancements for Irrlicht all over the web, like alternative terrain renderers, portal renderers, exporters, world layers, tutorials, editors, language bindings for java, perl,python, and so on. We are providing now an official Irrlicht Engine wiki. It is empty yet, please help us to fill it. It also contains readonly access to development plans and internal discussions of the Irrlicht Engine team. Background: The wiki at irrforge.org is down for some time now and altough some very helpful people provided alternative wikis for Irrlicht, we now decided to host it ourselves to prevent the history from repeating itself.
Support for Irrlicht.NET, the wrapper written in Managed C++ which makes Irrlicht available for .NET languages such as C#, VisualBasic and similar will be dropped with the next release. Instead, we encourage to use Irrlicht.NET CP, which is a separately maintained sourceforge project with much more functionality than Irrlicht.NET.
It is very easy to switch from Irrlicht.NET to Irrlicht.NET CP, and it also has the advantage that your projects will run on Mono and on other operating systems such as Linux as well then. Extending Irrlicht scene nodes is also possible with this library. We just released version 0.7 of irrEdit, the free lightmap generator and world editor for Irrlicht. It is now compatible with Irrlicht 1.3, supports terrain scene nodes and has the ability to show, edit and store custom scene nodes via plugins.