If neither player can take a turn, because all locations are obstacles they can't get by, they may agree to discard all of the face up cards on the top of the piles, and continue play from there. If they do not agree, the game is over. If they do agree, discard all the face up cards on the top of the piles, and turn over the cards below them. This helps keep the game from ending too quickly.
Treasure counts as an item. That means it can be discarded to get by a troll, or randomly stolen from you by a thief.