To examine this issue, we need to differentiate between Single Player (SP) and Multiplayer (MP) gaming experiences as they are quite dissimilar. Obviously, what you choose to do while playing SP, is between you and your computer, while playing online with others presents myriad opportunities to explore your creativity and imagination outside the limitations imposed by plot and dialogue imperatives.
Within the genre of SP RPG’s, we find two other divisions; those based on class distinctions such as D&D and those where your character can develop anyway you choose as in Oblivion or Gothic. It goes without saying, that people who choose a particular class, such as Paladin, or Wizard will have certain restrictions imposed on them which, in a sense, force them to ‘role-play’ to some extent. You can’t be an evil Paladin and your wizard won’t be very effective running around in plate mail armour, but is this ‘really’ playing a role?