I'm amazed no one's mentioned The Witcher 2 yet. Perhaps it's just 'cause I'm a dirty console scrub but that game can be ludicrously difficult, even when you're on easy. I lost count of how many times I've seen that damned "GAME OVER" screen. Mostly it comes down to the fact that on Normal, Geralt is about as sturdy as a wafer. Three or four good hits is generally all it takes to put him down, while your enemies (even the weaker ones) can take a pretty sound thrashing before they finally die.
I'm about half-way through, but I think I may re-start on easy 'cause I'm sick to death of... well, death.
Oh, and Infamous. I don't mind that Cole isn't an invincible god, 'cause I kinda like the idea of him just being a guy with powers rather than a superhero, but the problem is that your enemies are all eagle eyed sharpshooters who can spot and shoot you with perfect accuracy from three blocks away. Perhaps the raysphere also gave everyone 20/1 vision.