This is a game inspired by the spewing eruptions of volcanoes. The setup leaves an empty space in the center of the board, akin to the caldera of a volcano. Capture the winning pieces by causing eruptions!
Using the same erupt-and-capture mechanism as Volcano, Caldera changes just about everything else. The following play summary requires no prior knowledge of Volcano, but does assume a basic knowledge of Looney Pyramids.
Using 6 rainbow stashes, four of the colors in each stash are set up on a Volcano board in nests. Since there are only 24 nests, the center of the board is left empty. The 5th color of each stash is used for caps (generally black, the opaque color). The players move caps to cause eruptions to capture pieces, but also have the option each turn to execute a Power Play: return a previously captured piece to the board. The game ends when one player has captured 3 monochrome trios--that player wins.