From the back of the box:
You all stand at the entrance to the dungeon, but only one will enter: the bravest, the craziest, or maybe just the one who hasn't had a chance to flee yet! To see who has the guts to enter, take turns setting aside equipment or adding monsters to the dungeon. Are you tough enough to hit the dungeon? Or will you let someone else go down -- and hope they stay down? Welcome to the Dungeon is a subtle game of "chicken." Don't get cold feet, but enjoy icing your opponents!