Copyright (c) 2001 Joćo Pedro Neto

The game is played on an empty 5x5 board.

MOVE - On the first move the first player drops one of his stones on an empty cell. After that, each player may:
Drop two stones making no captures.
Drop one stone to capture enemy stones. This may happen if the stone is dropped inside a 2x2 cell area, with at least 2 stones, with the same pattern (rotational patterns are allowed - mirror patterns or opposite colors are not allowed) that another non-intersecting 2x2 area. Then all enemy stones on the matched area(s) are captured.
A move matching two or more patterns at once, all non-overlapping, captures all enemy stones inside those areas.
If it does happen in two overlapping ones, the matcher decides which area is captured.
KO Rule - The player must not drop a stone for capturing on the chosen 2x2 pattern area where one of his stones was captured on the last opponent's move.
GOAL - Wins the player that captures 9 stones or stalemates the opponent (i.e., places the last stone on the board).

An example

If White plays a stone at cell [1], he will capture the 4 marked black stones. Notice that the group on the bottom-left is not capture (mirror patterns are not capturable).

Ko rule

Black has just played d4:b3 (using the patterns bc34 and de34). Now, White cannot play on cells b3 and c3, because those cells are included on the 2x2 area used for capture.

A variant, is to change the goal for the following rule: When no more moves are possible, wins the player with more stones onboard (that is, all cells are occupied, or only remains empty KO cells). But if a player cannot end his turn (i.e., only can make one drop move) the game ends and wins the player with more stones onboard.