To fully appreciate this clever three-mover solvers should first
look for two prominent set play variations.
Solution: Set captures give the white queen access to d4, and
White replies with battery shut-offs - 1...Bxd4 2.Sf6+ Bxf5
3.Qxd4 and 1...Qxd4 2.Sc3+ Bxf5 3.Qxd4. There is also
a third set variation 1...Qe5 2.dxe5+ Bd4 3.Qxd4. The key,
1.Bc8, surprisingly abandons the battery and threatens
2.Ba6+ Kxe4 3.Qxc6. The captures on d4 defeat the threat
by leaving a flight at e5, but White can move the knight away
from e4 to threaten 3.Ba6 mate. It turns out that each time
there is only one safe square for the knight which avoids
capture or self-interference, and this reciprocally changes the
set continuations - 1...Bxd4 2.Sc3 any 3.Ba6 and
1...Qxd4 2.Sf6 any 3.Ba6. There is a considerable amount
of by-play. 1...Kxe4 2.Qxc6+ Kd3 3.Ba6; 1...Rh6 2.Sxg5 any
3.Ba6; 1...Qf6 2.Sxf6 any 3.Ba6 and 1...Qe5 2.Qxe5 any
3.Ba6, a third changed continuation.
Jacob Hoover: This was a great chess problem.
Dafydd Johnston: I like the element of paradox in this
problem. The bishop battery is essential to the set play,
allowing White to answer either capture on d4 by interposing the
knight between queen and bishop with check. Yet the key abandons
the battery and leaves the knight hanging. Black defences to the
threat allow White a safe square for the knight, this time
playing to the other side of the piece which self-pins on d4.
The game-like pawn structure is nice too.