Fallout 3. =) On the hardest difficulty, I was still able to beat Deathclaws at a low level. Sure, I go through ammo like crazy, but I don't think my character has been killed since I started playing (apart from blowing myself up on purpose).
The thing is, though, once you get used to playing a game, or a style of game, it becomes pretty easy. And it's a matter of perception, too. Like, I would say the Prince of Persia games from SoT onwards seem easy, because the ability to instantly recover from death means I don't notice when I die.