[twoxproblematic]

Not answering your question, but among my gamedev circle, "fun" is seen as a useless word because there are so many different possible meanings (challenging, soothing, exploratory, nice graphical effect feedback, nice music, social, etc) and often are contradictory with each other. We've seen countless times people setting merely "fun" as their goal, and then getting horribly depressed when the nebulous "fun" is never struck upon, with no clue how to make any ground in that direction.