While it's not an RPG or a FPS Red Dead Redemption is an excellent open-world game.
I just got it Friday and so far it's exceeded all of my expectations.
The Undead Nightmare addon is a lot of fun too.
Sacred 2: Fallen Angel is a good open world RPG. Some say it's just a mock-up of Diablo but I've never played that so I wouldn't know.
There isn't much customization in your character, only hairstyle and race. I was quite disappointed when I couldn't change my character's gender, mainly because I was tired of nearly every female in every RPG (including this one) wearing extremely skimpy/ kinky outfits. I could go on about that but I would end up just pointlessly raging about it. But the lack of customization in the initial character creation is at least partially made up for with the many armor slots and hundreds of different armor pieces for each race.
The combat is fun, but you may end up being surrounded by huge hordes of enemies. Also, there are about 16 hotkey slots to equip to as many spells/ weapons/ potions as you want. Also, there is no level scaling, so you don't have to worry about a repeat of Oblivion ( :shakehead: ).
The world in Sacred 2 is massive. Everything is rendered in front of you as you go so there is very little loading. If your thinking that this game must have a 5 foot draw-distance the camera is far above your character so you don't see everything being rendered. You can pull the camera up close to your characters back but it severely limits your range of sight.
As for exploration, you can explore most of the world, but there are some densely forested areas that you cannot go in and you cannot fall or climb down any cliffs.
And the menu system is pretty complex, there's lots of stats and attributes and skills and such. So you may be confused on what to do the first few times you level up. I suggest you read the manual, because I had no idea what the hell I was doing on my first playthrough of that game.
All in all you probably didn't even read all of this. But Sacred 2 gets an 9.5 from me.
You may want to try some of these games to:
Divinity 2: The Dragon Knight Saga
The Risen series
The Elder Scrolls
The Elder Scrolls
The Elder Scrolls
The Elder Scrolls
The Elder Scrolls
The Elder Scrolls
The Elder Scrolls
The Elder Scrolls
And some more Elder Scrolls.