Copyright (c) 1981 Marco Donadoni, International Team

This game is played on the following board with the following setup:

RA CELL - Each player has a special RA cell. In the diagram, the black RA cell has a blue dot, the white RA cell, a green dot.
STACK - A stack can have 1, 2 or 3 (not more) stones of the same color.
A stack with N stones must move exactly 4-N cells in a straight line of empty cells (no jumps allowed), except if it reaches (a) the board edge, (b) the enemy RA cell, (c) another stack (of either color) or (d) by capturing (see next).
If the stack ends its movement over an enemy stack, the enemy stack is captured. Capture is not compulsory.
However, stacks with size N can only capture stacks of size less or equal than N.
A player may move only part of the stack (the moving range depends on the size of that sub-stack).
The moving stack (after moving the required number of cells) can also land over a friendly stack, stacking them together providing that the final size is not superior to 3 stones.
TURN - On each turn, each player move one of his stacks.
When a stack reaches the enemy RA cell, that match is over.
If the stack has 1 stone, the player gets 1 point. If it has 2 stones, he gets 3 points. If it has 3 stones, he gets 6 points.
The match also ends if a player captures all enemy stacks. 
In this case, the player gets 3 points.
Then the losing player starts a new match, until one player gets a minimum score of 6 points with at least 2 points of advantage to his adversary score.
An example

Black can split the stack of size 3 in the upper side, moving two stones over the stack of size 1 to the right. He could not, however, move just one stone, since it would need to move three cells before stacking.

In the center, White could capture the black stack to his left, since it is within its moving range, and the black stack is smaller.

Either Black or White could win in this position. If it's Black's turn, he could move his black stack of size 1 over the white RA cell (And getting one point). 

White could do the same by moving three cells with just one stone of his white stack of size 3 (also getting one point). However, White could try an optional move, in order to win by a larger number of points. 

I wish to thank Dieter Stein for valuable game information.