The Washington Post desribes
Settlers of Catan as
a necessary social skill among entrepreneurs and venture capitalists (one tech chief executive calls it "the new golf"). It's joined Monopoly as a boardgame played by people who aren't interested in boardgames.
Most boardgames, unsurprisingly, appeal more strongly to boardgamers than to those outside the hobby.
Arkham Horror is a blast. It's a game that not only engages intellectually but emotionally. While you play, you find yourself actually caring whether you can remove those little cardboard gates from the board fast enough to stop the Great Old One from appearing in this imaginary town. However, those who aren't used to boardgames will look at the long rules and the three-five hour playing time, and say "No thanks." If you're not used to it, speding three hours sitting down, while trying to keep track of a set of rules that read like part of the tax code, doesn't appeal.
There are some boardgames that don't have this problem. There are the classics: chess, checkers, Monopoly, Trivial Pursuit, Scrabble. Boggle tends to go over well. But there are new games that most people seem to like.
Betrayal at House on the Hill had a bad reputation among boardgamers for its poorly explained rules, but I've never introduced it to a group without at lest one person vowing to get their own copy.
Caracassonne seems to go over well among non-boardgamers, especially if you play with the house rule that you pick up a new tile at the end of your turn. That speeds play a lot.
What do you think makes a good introductory board game?