While studying the new problem all of a sudden I realized that this position was about invasion too. If white just plays Qh7 he will probably win too, according to Rybka. But Spasski decides to flick in the move 1.d5 first. That adds whites bishop to the equation. If black simply plays 1. ... Kg8 to prevent the invasion, then white plays 2.dxe6. Black cannot take because that loses a piece due to. . .
. . .overloading.
It is not so easy to see, but the black queen is overloaded since it has to protect the knight, the bishop and rook c8. A lot of tricks in the position are based on this overload idea. In this old post more than two years ago I investigated overload already and found that in 62 of 63 problems of a certain problemset overload played an important role. In fact in problem 385 earlier this week overloading of the queen played an important role too.
This is encouraging. Within two problems I already found two major principles that play a role in a whole lot of complex tactical problems. Now let's see if I can improve my recognition of these two principles to the max!
White to play and win
16 hours ago