They don't have to. They have to look like, or be named (or both) similarly enough that the average consumer could mistake the Rubix for be associated with, or tacitly endorsed by the original Rubik's Cube.
This, in it's current form, is doomed to be redesigned unless they can secure rights to use the likeness of the Rubik's Cube.
I've been through this on both sides. The threshhold for Rubik's Brand Ltd. is very, very low.
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