Your objective is to clear the King Dugan's dungeon of monsters by using only your Really Big Sword™ (that will defeat almost any monster in a single hit) and your wits. Each room is a separate area that has to be cleared in a single session. If you leave a room without completely clearing it, it will be restored to its initial state when you return.
Use Arrows or numkeys to move, Q or W to rotate your sword. Follow the in-game instructions.