I've played a couple of games on the page including Riven (and Myst, its predecessor). They, and games like them are incredible examples of cutting edge graphics and animation. What I wonder about is long-term playability. Once I figured out how to solve all the puzzles and complete the game, I gave it away because I never touched it again.

Is there a line between the kinds of games that are interesting and engaging for a few days and are never played again vs. classics like Monopoly that are played over and over?

I grew up playing strategy games from Avalon Hill, since bought by Hasbro. They used to specialize in historically based strategy games that could be played again and again. What games have people played that blend repeat playability with cutting edge technology?