I have a post-it on my desk. the post it says:
it is a note to myself as I would have liked to use Robin’s classification (Mechanics, Dynamics, Aesthetics. more about it here: www.cs.northwestern.edu/~hunicke/MDA.pdf) and show how it can be used to describe the third step as Experience.
the beauty with the notes to self is that you change your mind over time and now that I’m thinking about it, I see Experience more as a 4th level, where it includes memory and goals, together with rules, users and context.
does it make any sense?