Unity3D

Unity3D is a very powerful program for creating virtual worlds that is used mostly for creating 2D and 3D games. However, it can also be used to build the city of Cyberia which can be experienced either via your computer monitor or even through the Oculus Rift, allowing you immerse yourself in the virtual 3D environment. It's free to anyone to download and use and if you are a newbie to using the program it has very detailed tutorials to guide you in learning the program. The program can be downloaded here:

Unity3D

Here are some examples of what can be done with Unity3D. Some videos have advertisements so you may have to wait until those are done to see the video: