Have you ever wanted to see and touch four-dimensional objects?
This is a real-time visualization app that renders four-dimensional regular polytopes such as tesseract.
You can intuitively manipulate these theoretical existences with simple touch gestures.
Theres an easy tutorial, which teaches you the way of handling the fourth dimension.
If you are more interested in the 4D polytopes, connect to an internet encyclopedia with an in-app browser and get further information.