Creating a 3D simulator


I have never used unity 3d before, but I've heard and seen great things. I'd like to make a simulator of a small 3 Dimensional scene (like 40 by 60 feet). There might be some elevation, and some simple physics will be required, as the user could interact with balls, and other small shapes. The user would have a robot that they could drive around and interact with the scene. Basically, it's a small simulator.

Now, bearing in mind I've never used unity 3d, and would probably need to do all of this in under 20 hours of actual work, could I do it? How complicated would it be to do this, if I created a scene in 3ds max (I'm very experienced in that program) and just import it in?

I really appreciate any feedback.

Unity imports almost everything, including 3ds max.