There are three different modes of play, but all incorporate the same Battleship-esque structure. The goal is to reach your opponent's Dragon Lord while blindly navigating about his or her gridded dungeon. Your opponent will place walls in different places to try to hinder your progress, and you can choose whether or not to play with chests, cards, and combat.
Of course, this is one of those "only in Japan" things (those Japanese folks just love their Dragon Quest), so if you fancied getting the game you'd have to import the 5800 yen ($53 USD!) item from somewhere. You would probably also need to have a good understanding of Japanese to read the rules and cards.
Or, you could always just wait for the video game based on this board game that was based on a video game to come out. And yes, that's just crazy talk. Check after the break to see if you've sunk my Dragon Lord. Oh, and there's more board game pictures, too.