Fairy chess is not supported. Gustav only solves orthodox mates and solves these up to 32 moves. As an output you get the key move. Solves orthodox direct mates, emphasizes clear code at expense of speed. Prints diagrams using your Truetype fonts, Manages archives which can contain thousands of problems.
Retractor is a program for Retrograde Analysis chess problems.
It allows one to set up a position and play backwards from it.