If one were to go back and play old NES games like Contra or Kid Icarus, I think the nostalgia would be overwhelmed at some point by the cruelty inherent in these older games. There's no saving. There's little room for mistakes. And if you fail over the course of many hours of play, you start over. Who has the time or patience to deal with that kind of thing today? Who would pay money to experience that again?
The makers of Dark Souls apparently thought somebody would. The game has no pause button. There's very little instruction or story. The game is cruel, and when you die, you lose all of your souls, the game's currency. When you go to checkpoints and heal, all of the enemies in the game respawn.
One might think Dark Souls is just a needless nostalgia play, but they only adopt old gaming rules when they support the game's goal: give the player constant stakes. Give them a strong incentive to take care. Make them fearful to fail and jubilant at success. They hit that mark perfectly. I'm no gaming expert (I died 30+ times in the first few hours of play and nearly gave up), and even I have found the game incredibly rewarding. Fromsoft basically made a deal with the player: deal with our hurdles, and we'll reward you with incredible rewards in detail, feel, loot, and fun.
This is an incredible bet for a gaming studio; I can think of no other recent game that attempts to make this deal with the player. But after two excellent games in this vein (Dark Souls' spiritual predecessor is a game called Demon Souls and is similar), I think we may see a resurgence of the high-stakes game. Jaded players need stakes, whether they realize it or not. Here's to more stress and more rewards in gaming's future.