Already familiar with it; doesn't make it right, or justifiable. And there's plenty of case law in both directions on reverse engineering and cloning; the exact boundary would depend heavily on the details of a specific case.

In any case, it'd also be much harder to prove any harm caused by a variant like this, which is designed specifically to be un-fun, as difficult as possible, look nothing like the original, and not have any commercial interest at all. Which makes the presumption of illegality entirely inappropriate.