DEEP IN THE QUANTUM RABBIT HOLE:
It has PHASE and follows the actual math of QM. Moves (both classical moves (Cm's) and quantum moves (Qm's)) apply quantum gates involving 2 or more squares, and collapse happens whenever two different type and/or color appear on the same square. Collapse is random in accordance to the laws of QM and so introduces luck into the game, with the addition that capturing Cm's remove the wave amplitude in the destination square off the board (Qm's can't be used to capture).
We are allowed to make moves for e.g. a Knight where is some amount of Knight at the origin square and the destination is within 1 (Cm) or 2 (Qm) Knight moves away. Cm's apply the NOT gate while Qm's apply the sqrt(NOT) gate. Every piece except unprompted pawns can make Qm moves, and even pawns can get involved in the fray when they i.e. capture half of a rook's wavefunction.
How does phase matter? Consider white knight moves from B1 to C3. White doing the Qm version of this move twice is applying sqrt(NOT) twice, which is the same as applying NOT (a classical move). However, if white moves Qm, Cm, Qm, the Cm move (which will not appear to have done anything when it is done this way) means our total gate equivalent to applying the NOT gate 1/2+1+1/2 = 2 times, i.e. doing nothing at all. Thus a move that seems to do nothing (the intermediate Cm) actually had an effect. In a real game, more complex phase phenomena show up.
When there part of a piece in the way (and only one path from A to B) we apply a CNOT gate for a classical move, which means that the ordinary NOT gate is "controlled" by the absence/presence of the blocking piece. If there are multiple paths through blocking pieces, multiple other pieces can get involved. Handling all of this complex and intuition is built gradually, mastery is hard but possible. In general the game favors parsimonious rules over what a human would expect.
And by the way, two of the same piece/color combination are identical particles (spin 1/2 fermions).
BRING A FRIEND:
Overall the game plays well. It has a balance of obvious and deeper strategy and tactics with luck thrown in (whenever a collapse happens). There is no easy trick to force a draw, etc (no, splitting the king over and over again won't work. The opponent can capture most of your king, split his pieces to fill all vacant squares, and mop up your remaining sliver of king).
The graphics are pretty (don't use the 3D view). Two main downsides: I don't think there are enough people for reliable online play yet; there is no AI to speak of (it is horrible and it will be much harder then chess to develop a good AI). However, this game makes a good cofeeshop topic with a friend. And the fact that developing an AI will (I think) be so hard means we can hone a skill that is both fun and beyond what machines can do, a claim few board games have.
