Fun in definition of enjoyable: yes Fun in definition of funny: no
No game is just 'fun'. Some are challenging and quite a pain in the ass. Some are light hearted and other extremely realistic and immersive. Train simulator and goat simulator are both games and even both simulations, and still they are totally different. Train simulator is extremely realistic, while goat simulator is ridiculously silly. Some would call the first fun, other the second, a third group would perhaps even call both fun, while another group like me probably would never play either of it.
'Fun' is no exact definition. Fun is subjective, everyone has a different taste. That is why games are art like drawing. No game will ever be 'fun' for everyone. So defining a game has to be fun, does define nothing at all, because what is fun for you could be annoying or boring for someone else.
That is the same reason, why opinions on CC divide sometimes quite heavily aswell.
