The Hypercube is one of the 3 four-dimensional objects.
How to obtain:
1: When you have high enough intellegence you can challenge Chess Master Chase (in the U of S) to a chess match. When you accept, he will give you a Hypercube. (Note that you don't acually have to play him in chess)
2: In the police station there is an inmate named Nigerian Prince. He will ask for $10,000 to get him out of jail. Give him the $10,000 and he will reward you with a Hypercube.
3: Find The Dimensional Drifter and buy the Hypercube from him for $100,000.