Minus Cube
...that the Minus Cube mechanical puzzle , first manufactured in the Soviet Union, is a 3D variant of the 15-puzzle?
...that the <b id="mwAQU"><a href="./Minus_Cube" id="mwAQY" rel="mw:WikiLink" title="Minus Cube">Minus Cube</a></b> <a href="./Mechanical_puzzle" id="mwAQc" rel="mw:WikiLink" title="Mechanical puzzle">mechanical puzzle</a> (<i id="mwAQg">pictured</i>), first manufactured in the <a href="./Soviet_Union" id="mwAQk" rel="mw:WikiLink" title="Soviet Union">Soviet Union</a>, is a <a href="./Three-dimensional_space" id="mwAQo" rel="mw:WikiLink" title="Three-dimensional space">3D</a> variant of the <a class="mw-redirect" href="./N-puzzle" id="mwAQs" rel="mw:WikiLink" title="N-puzzle">15-puzzle</a>?