This is the fight of Captain Silver (the pirat) against James Cook which both want to take possession of the treassure island. And the rules are:
There is a 8 x 8 game board, every of the two players has one ship. At the beginning the ships stand on two diagonal corners of the game board. Additional there is an island of 2 x 2 size. The position of the island is determined by accident, so that at least two free fields remain on every side. The ships move alternately. A ship always stands on two horizontal, vertical or diagonal neighbouring fields.
A ship moves always one field forward and can turn with an angle of 45 degrees to the left or to the right. There is one exception: At a corner (the harbour) a ship can turn with an angle of 90 degrees. If after a move of a ship the other ship stands on a neighbouring field then this counts as a hit for every field. After hit number seven a ship sinks. A ship also sinks when it drives on the island or at the border of the game board, that means at land. The ships may not ram each other. If there is a possibility to prevent ramming, then this move must be made even if the own ship sinks.
There is also a rule that it is not allowed to move in circles. Every whole circle (that means more than 7 times only left or only right turning) counts as a hit. When one ship is sunken the other ship has to make another 7 moves, after that it has won. To gain the winning of the whole game you have not only seven, but seventy times seven moves. If there are both ships on the board after 490 moves, it's a draw.

In this picture Cook (white) has just moved and made a hit on Silver's ship. After you have finished a game you can analyze it once again: first press "1" and "3" to change into the 2-player-mode. Now you can take back a move by pressing "t" and replay by pressing "r".
You can change the graphics mode by pressing "m". Use Ctrl + arrow keys to go around the game board and use "+" and "-" to zoom in and zoom out the picture.
For the controlling of Cook's ship use the arrow keys. The pirat ship can be controlled by D-F-G.