It uses the xboard/winboard chess-engine protocol to communicate.
Apart from 'regular' chess (also known as the Mad-Queen variant),
it can play Capablanca chess, gothic chess, knightmate, cylinder chess,
-berolina chess, superchess and courier chess.
+berolina chess, superchess, makruk (Thai chess) and courier chess.
Fairy-Max can be easily configured by the user to play other variants as well,
by modifying the ini file.
This ini file describes the rules of movement
Note that to be able to play the chess variants,
you will need xboard 4.3.14 or later.
+Fairymax supports multi-PV mode: by specifying a non-zero multi-PV margin in the
+Options -> Engine-Settings dialog of XBoard, Fairy-Max will not only print the
+principal variation for the best move, but also for every move that approaches
+the score of this best move to within the set margin.
+(If it does not find the best move on the first try, this might lead to printing
+of a few extra lines below the threshold.)
+
The fmax.ini file from which Fairy-Max by default takes the piece and game definitions
is a self-documenting text file,
which contains instructions for how to define new pieces and chess variants.