The difference between action/adventure and RPG is choice and consequence. Action/adventure generally has little to none, usually if it has any its a single choice at the end of the game. RPGs allow you to make choices and the world reacts to those choices.
I think the keywords for a what makes an RPG are agency and reactivity.
I get to choose what I do, and the world is geared to take my actions into account and respond to them.
The only way to summarize every version of "what makes a true RPG" would be to say: Role playing game is a game that strives to opt you with a wide variety of freedoms,choices and consequences that you can explore-/&-exploit to your personal liking.
I would agree that choice is probably the central pillar of "RPG-ness", but to me it begs the question how much choice is enough (or too much)? Should your character be able to financially support themselves via tradeskills instead of adventuring? Should you be able to purchase property, or control your character's diet, or spend your time romantically pursuing other characters? Obviously this varies between games, but if player choice is what defines an RPG, is the game that gives you the most choices the truest RPG? That is the question I intend to raise in this thread, as the mechanics and/or narrative of Infinity Engine games somewhat limit the player's choices (nothing against Infinity Engine games for being what they are, but perhaps their RPG-ness is limited). Where are the games that actually do this?
Edited by mcmanusaur, 24 May 2013 - 06:49 AM.