Originally Posted by Pladio
I think it is, but I don't think your definition is correct. I also think some definitions can never be all-encompassing.
A quick example of this is the Google Definition of a "chair".
The definition states it typically has a back and four legs. However, if you showed me a picture of a chair with five legs, I wouldn't tell you it was not a chair. Additionally, if two people decide to sit on a chair because it is a relatively large chair, then I also would not say that it no longer fits the definition, and as such is not a chair.
In my mind your definition of RPGs is too narrow for what I consider to be an RPG.
Hope that makes sense.