Funny enough, I think Bolivar listed the defining factor that separates an RPG from other games in another thread about this topic. The more I thought about it, the more I felt he was correct. RPGs are games that have some element of RNG as a major gameplay mechanic. Basically the game has to have a virtual dice roll mechanic to determine an outcome for a core element of a game. Essentially, RPGs are games that have RNG induced critical hits. This would technically end the ''Is Zelda an RPG'' debate, because the series does not feature RNG as a core mechanic.