If regular Rubik’s Cubes just aren’t tough enough for you, try the Rubik’s Cube Earth.
Rubik’s Cube Earth costs about US$ 20, and should be significantly harder than regular Rubik’s Cubes because it lacks the distinguishing colors.
Plus, you also have to know what the Earth actually looks like [via Geekologie]. Happy Puzzling!
Tags: Rubik’s Cube