It depends ...
Do you mean what cant miss in RPG?
That would be immersive world, character customization, interesting story, enough possible reactions in dialogue so i dont stuck in "i cant pick any" too often, deep characters, as many differences between "classes" as possible. :P
The usual stuff ...
Or do you mean what makes great RPG?
That would be replyability, choices that actualy matters (wich we were promised for last decade almost every time, but never delivered), the options to solve problems creatively.
Or ... do you mean what makes exceptional RPG?
That would be somethin we never had before, some original element.
- For Bloodlines it was Ocean House ... whole level where is litteraly nothing, except you and many scary sounds. :3 Or its finale, wich i will not spoil, but it was hilarious.
- For KotOR (especialy second) it was depth of phylosophy that was implemented ... wich moved the whole idea of Light and Dark side of the Force to whole new level.
- For Elder Scrolls it was giant open world, where you can do litteraly almost anything.
- For Fallout it was (speaking for myself) that quite unique merge between multiple "punk" styles.
And ofcourse the depth in wich stats of your character affects your game ... starting with shorter sentences for low Int. characters, ending with amount of muscles for more Str. characters ... well, and certainy Vault tech, if you know what i mean.
etc. :P
