The Rules for Volcano

Arrange 25 Nests of small+medium+large pyramids each as shown, with small black pyramids along the diagonal. Moving:  Only the black pieces, which are called Volcano Caps are moved directly.  A volcano cap can be moved to any adjacent square, including diagonals.  Then, if possible, the volcano that was uncapped erupts in the same direction, distributing pieces along the row defined by the eruption.  The eruption stops when the original volcano is empty, or the eruption reaches the edge of the board, or the eruption reaches another volcano cap.  The same player keeps moving volcano caps until an eruption occurs.  House Rule:  you can't return a cap to the same square unless an eruption occurs.  This prevents endless repetition, but a turn can still have many moves. Capturing:  After an eruption, any erupted piece that has landed on a piece the same size is captured.   Several pieces may be captured in one eruption, or none, depending on the relative sizes of the erupting pieces and the top piece in the destination square. Scoring:  The players continuously rearrange the captured pieces to form the highest scoring combinations.  Solid Nests consisting of 3 pyramids the same color score 7 points.   Mixed nests consisting of one pyramid of each size score 5 points.  Other pyramids score 1 point each. Game Ends: when one player has captured at least one pyramid of each color.  The player with the high score when the game ends (not necessarily the player who ended the game!) is the winner.

You can move volcano caps around virtually forever without causing an eruption, so a specific objective "make stack x erupt in direction y" is frequently possible with enough preliminary motion. From the starting position, the first player has manouvered B2-C3, C3-B3 and B3-B4, which causes the eruption to B5.