The Rubik’s Cube core has six turning axes, each of which supports 90° turns. The Master Pyramorphix puts these axes in the centre of each of the six tetrahedron edges. But the tetrahedron only has 180° symmetry about its edge centres, and this discrepancy gives the Master Pyramorphix its charm. In a sense, the Master Pyramorphix offers two puzzles in one:
You can restrict yourself to 180° turns, and if you do, the Master Pyramorphix will turn from isometry to isometry, and thus retain its tetrahedral shape. It may be scrambled but it will never be jumbled. This version of the puzzle is almost exactly equivalent to taking a Rubik’s Cube that has been scrambled with 180° turns only, and solving it using 180° turns only (this is be no means an easy task — you should try it some time).
If, however, you start making 90° turns, pieces of your Master Pyramorphix will be moved into non-isometric orientations, and the puzzle will lose its shape and become jumbled, adding a whole new level of complexity.
When you first pick up a Master Pyramorphix, jumbling is highly unintuitive. Because a 90° turn does not return the Master Pyramorphix to its tetrahedron shape, it looks like only half a turn, and the discovery that all its axes are fully functional when apparently half-way through a turn is astonishing. In reality though, you’ve made a perfectly legal 90° turn, as determined by the mechanics of the core — the symmetry of the outer shell is irrelevant.
The Master Pyramorphix is the second in the Pyramorphix series of puzzles, which starts with the two-layer Pyramorphix, and continues on up to seven layers. By virtue of its shape it is related to the other tetrahedron puzzles, such as the Pyraminx series, but as an edge-turning puzzle it has very little else in common with them.
Far more significant is the fact that this puzzle is essentially a Rubik’s Cube shell variant, and is therefore closely related to the Rubik’s Cube and the other myriad shell variants of that puzzle.
In terms of play, the edge-turning nature of this puzzle, and its cut, make it feel similar to other edge turning puzzles like the Curvy Copter and the Helicopter Dodecahedron.