Kambi VRML game engine is a free/open-source 3D (game) engine. The engine is written in clean Object Pascal code, and we have an excellent support for the VRML / X3D 3D data (although other 3D model formats are also supported). See here for detailed documentation and downloads for developers.
French
Kambi VRML est un moteur libre de jeux 3D. Le moteur est écrit en Pascal Objet. Il possède un excellent support des objets 3D VRML/X3D.