Someone else mentioned the Witcher earlier, but I'd like to give a slightly different perspective: (SPOILERS AHOY, although said spoilers can be played in the demo as well so yeah)
When you have to decide whether you want to let them burn the witch or escort her to safety at the end of chapter 1 (i.e. be a total asshat or a knight in shining armor), there is a definite DIFFICULTY difference between the two choices. In both cases, you are met with the Beast, but in one you only have useless Abigail to help you, whereas in the other you get the whole town to help. Despite having leveled properly, used alchemy to get me a bunch of potions, got myself a meteor sword etc etc, I still had to load that encounter a LOT of times before I somehow (through some fluke of the Group Style I think) managed to kill the Beast. After that, I still had to kill a bunch of villagers on top of it all! As a final stab, I was arrested on entering Vizima. Whereas in the 'evil' option, I breezed through the encounter in moments, and what more I would be allowed to enter the town no questions asked.
If I would have been forced to fight the Beast alone a couple of more times, I might just have decided to go with the evil way out just for the sake of being able to continue the game.
My point here is that generally there is no difference in difficulty between 'good' and 'evil', just a difference in dialogue and rewards usually. At least in Bethesda games, being 'evil' lets you steal lots of good loot early and make money, but when it comes to quests they're every bit as conservative as the rest.
What I'd like to see is an RPG where there is some general definition of 'good' and 'virtuos', which the player can either choose to follow or abandon (or do a bit of both), in which deviating from the path will generally make the game easier, and staying good would make the game harder. It'd be a morality tale, while simultaneously doing away with the silly difficulty selector. Say for instance the protagonist is a monk, sworn to nonviolence and a simple, ascetic lifestyle with no or few worldly possessions. S/he then sets out to rescue the world/monastery/kingdom etc, and is constantly bombadeered with the opportunities of life outside - magical weapons and armor, untold riches, hot sex scenes with naughty wenches, lots of opportunities to make a quick buck and so on. The Hard game is one where the monk remains pure and completes his/her incredibly hard task through perseverence and personal skill, and looks more or less the same at the end as at the beginning. The Medium game is where the monk makes some concessions to the difficult task at hand, gathers some weapons and maybe some spare cash, does bunch of shady jobs etc, all for the greater good. The Easy game is where the monk goes all-out RPG on the world, loots corpses and houses, steals and murders, gathers money on a pile, always picks the most lucrative option through a quest and so on, ending up at the end boss as a veritable demi-god.
Here we bump into the next problem, though: content. Since when is the content of RPGs so very much determined by the amount of murdering, looting and pillaging you do in them? Poor, pure monk, we shall never know thee...
When you have to decide whether you want to let them burn the witch or escort her to safety at the end of chapter 1 (i.e. be a total asshat or a knight in shining armor), there is a definite DIFFICULTY difference between the two choices. In both cases, you are met with the Beast, but in one you only have useless Abigail to help you, whereas in the other you get the whole town to help. Despite having leveled properly, used alchemy to get me a bunch of potions, got myself a meteor sword etc etc, I still had to load that encounter a LOT of times before I somehow (through some fluke of the Group Style I think) managed to kill the Beast. After that, I still had to kill a bunch of villagers on top of it all! As a final stab, I was arrested on entering Vizima. Whereas in the 'evil' option, I breezed through the encounter in moments, and what more I would be allowed to enter the town no questions asked.
If I would have been forced to fight the Beast alone a couple of more times, I might just have decided to go with the evil way out just for the sake of being able to continue the game.
My point here is that generally there is no difference in difficulty between 'good' and 'evil', just a difference in dialogue and rewards usually. At least in Bethesda games, being 'evil' lets you steal lots of good loot early and make money, but when it comes to quests they're every bit as conservative as the rest.
What I'd like to see is an RPG where there is some general definition of 'good' and 'virtuos', which the player can either choose to follow or abandon (or do a bit of both), in which deviating from the path will generally make the game easier, and staying good would make the game harder. It'd be a morality tale, while simultaneously doing away with the silly difficulty selector. Say for instance the protagonist is a monk, sworn to nonviolence and a simple, ascetic lifestyle with no or few worldly possessions. S/he then sets out to rescue the world/monastery/kingdom etc, and is constantly bombadeered with the opportunities of life outside - magical weapons and armor, untold riches, hot sex scenes with naughty wenches, lots of opportunities to make a quick buck and so on. The Hard game is one where the monk remains pure and completes his/her incredibly hard task through perseverence and personal skill, and looks more or less the same at the end as at the beginning. The Medium game is where the monk makes some concessions to the difficult task at hand, gathers some weapons and maybe some spare cash, does bunch of shady jobs etc, all for the greater good. The Easy game is where the monk goes all-out RPG on the world, loots corpses and houses, steals and murders, gathers money on a pile, always picks the most lucrative option through a quest and so on, ending up at the end boss as a veritable demi-god.
Here we bump into the next problem, though: content. Since when is the content of RPGs so very much determined by the amount of murdering, looting and pillaging you do in them? Poor, pure monk, we shall never know thee...