BOOMERANG

Copyright (c) 1982 Claude Duvernay

This game is played on an empty 9x9 square board:

There are the following set of pieces off board (as far as I can tell, there are two of each kind, except Ls and rectangles of size 3, which are four):

In the original game, each piece has two colors, one per side, so they may be flipped over (check rules).

DROP - Select one of the off-board pieces, if necessary rotate it and drop it on a set of empty cells.  Every adjacent enemy piece is flipped over, thus becoming friendly pieces. Adjacent means touching in at least one edge, not just in a corner. GOAL - When it is not possible to drop more pieces, wins the player with more points (one point per friendly stone; notice that each piece is made of several stones).

 

An example White's turn. If he drops the marked L, he will flip two black pieces as we can see in the second diagram.