Here a draft of how we made this web, this kind of project needs to combine video game techniques, web technology and 3D art.
1.- 3D Modelling
3D general draft of the concept.
2.- Assets optimization.
Poligon reduction for the web engine.
Painting the textures and materials.
UV mapping and textures.
Integration
Set all the 3D scene.
Web development.
Building the web page interface.
Make interactions.
Developing all interactions in scene.