Ok, I probably make it to easy for me,and narrow it up a bit but; for a game to be considered a real RPG (for me) it has to include.
1. The ability to play a role, and do choices based on how you imagine the character.
2. Moral dilemmas (in essence choices)
3. 'Internal' and 'external' development based (partly) on the choices you make
Beware, I live!
I am Sinistar!
Beware, coward!
I hunger!
Roaaaaaaaaaar!