Your task is to steal treasures from Willy, a rival rascal o' the high seas. Willy, it seems, has taken to throwing his plundered goods from the edge of a wooden dock (presumably as a less labour-intensive alternative to burying it randomly around the Caribbean).
This is where you come in. As Willy dumps his purloined wealth into the bay, it passes into your control. Typical of the genre, you must then move and rotate the falling cubes, matching them up with boxes of the same colour. Connect three or more matching boxes and they explode, disgorging their expensive cargo directly into your possession.