First step (to be able to import the project into Unity 3D) was exporting its elements as OBJ. files from Rhino.  I exported separately:  the project module, the terrain and the staircase.  I divided it into the parts and exported just one module of the project (because my computer wasn’ t able to process it in one file).  While exporting I selected Map Rhino Z to OBJ Y and I exported  Rhino object names as OBJ objects. I created a new project in Unity 3D.  I imported a new asset– the terrain OBJ. file from Rhino.  In order to not allow the player go through the terrain surface I selected the option Generate Colliders. I created a directional light.  I gave it a light blue colour and I decreased its intensity to achieve the willed atmosphere. I set soft shadows. and change the bias into 0.5 in order to have  better quality of the shadow contour. I created a first person controller and changed his location to make him able to walk on the terrain.  In character controller I increased the step offset value to make the gamer able to step up a the stairs. I imported other OBJ. files: staircase and one module of my project.  I assigned them new materials.  For the staircase and the terrain I used diffuse shader. For the project I downloaded transparent shadow shader which enable shading by transparent objects. I copied the module and rotated it forming my project final form. I imported a skybox package, then in render settings I set a sunny sky material. In order to publish the game, I selected Build and Run and I saved the game file in my hard drive. Below I am presenting the view of the player starting the game. ENJOY THE GAME!!!