I asked some friends who are not even very computer-savvy to try "Lost Pig" and they became engrossed after a few minutes of user-interface confusion. I had always thought the confusion would be enough to put off the average user (and still do not believe in IF as a profitable venture), but each of them greatly enjoyed the game and wanted to continue playing longer than my laptop was available to them.
One of my favorite sandbox gameplay interactive fictions. Rather than presenting a strong plot or developing fleshed-out characters, The Space Under the Window is an interactive free-verse poem with many different endings as well as paths to those endings. It is very rewarding to play repeatedly, even if one spends less than ten minutes exploring the possibilities.
I only wish it were more fully implemented, allowing more keywords to cause revisions to the narrative.