Tough Love - Can A Game Be Too Hard?

Thanks to Slate for its article discussing the excessive difficulty inherent in some videogames. The writer argues: "Some [games] are so freakishly, spoon-bendingly difficult that they take 10 hours of solid play before you've even begun to master the basics... I usually discard them in frustration after a couple of hours and wonder: What's the point? What adult has the time to master this stuff? Could it ever be worth it?" He continues: "The latest test of this thesis is Tecmo's new Ninja Gaiden, a game so punishing that even some hard-core players fear picking it up." Although the piece concludes: "Just because a game is hard doesn't mean it'll have a payoff", what games have you played that are insanely tricky to master?