Great topic.

I think there is a lot of disagreement over this subject. Here's my own definition, for what it's worth.

An RPG is a game that features 1) a set of tangible, appreciable statistics that directly correspond to intangible qualities like strength, charisma, and wisdom, 2) the ability to modify those statistics by earning experience points by defeating enemies and completing quests, and 3) the electronic simulation of die-rolling mechanics from pen-and-paper RPGs like Dungeons & Dragons to determine success and failure.

You are right, that genre is very diverse and people have very different opinions about it. But as I play Pen&Paper too, including D&D, I have some problems with people including games that have no player-choices in character-development into the genre.

That would both also exclude the player in the character-development.

There you have it, Suikoden II is a turn-based action adventure non-RPG game then.

Sorry, I nearly fell of my chair. Baldur's Gate is prime example of what true CRPG based on pen&paper RPG ancestry (which are origin of all RPGs) is. Glad you got more info on game genres. ;)

Okay, I've messed enough with people's minds.

There is not a thing that defines a videogame as a RPG.

What exists is a compendium of "traits" that people perceive as "RPG elements". Stats, character developement, the narrative that Khuutra mentioned and more. Not everyone agrees about all of those elements being RPG-ish, which is a bad start. To make things even worse, the presence of all of them isn't required for a game to be considered a RPG.

There are plenty of games that have RPG elements, and not all of them are RPGs. We can't deny that Devil may Cry have RPG elements. HP and "MP" upgrades, being able to choose which attacks to learn, etc. When we consider a game is a RPG, then?

When the RPG elements present in a game stand out more than everything else. And this is subjective. This is why Castlevania DoS is a 2D action adventure plataformer, but people may argue about it being a RPG. It depends on where people put he bar.

I agree with your statement; and as a simple definition to add - it would be the dominance of RPG traits in the game over other gameplay elements.

A story driven game that offers a non linear experience where the player can customize and improve their character over the course of the game as well as make choices on how the game progresses.

Very difficult to do in video games which is why I'm usually pleased when a developer has managed to incorporate it with any modicum of skill. Dragon Age Origins is really the main example as you had 6 different character storylines depending on the origins of your character. This directly effected some of my choices later in the game as I would think "If that happened to me, how would I respond?". That's pretty much the best we can hope at this stage.

As you said, it's very difficult to do as no AI has been able to accurately put together a storyline based on player actions. AI seems to have progressed so slowly compared to graphics it seems decades away before we'll have anything close to resembling an AI capable of this story developing feat.

In some ways, the Bethesda games have managed to incorporate the feeling of personal story through sheer freedom. Although the story remains the same for all quests, the intricacies are largely determined by player choice. This essentially ends up as a "what order to do the quests and what to do between them" rather then actual story development although the player experience is somewhat personalised.

That definition includes all MMA and pro-wrestling games for the past 10 years. In fact, it includes MMA and Pro-wrestling games more so than most actual RPGs.