The only direct action the players take in this game is to move the caps around on top of the other colored pieces.
Sometimes when you move a Cap, one or more pieces beneath it will erupt. But oftentimes you can move a Cap such that no eruption occurs, in which case you get to move a Cap again (either the same one or a different one).
In this way, a player can make many Cap moves in one turn, moving them around until an eruption occurs. Your turn ends as soon as one or more pieces erupt, no matter how much you moved the Caps around.
• Although Caps cannot be stacked upon, all other types of stacking are allowed. For example, it’s OK to stack larger pyramids on top of smaller ones. This can create some strange-looking towers.
• You can move any number of Caps any number of times, as long as nothing erupts.
• Your turn ends when you cause an eruption of any kind, even if you fail to capture any pieces.