Fun is subjective..... Games are more than fun. Games are about entertainment in a generalized term, it's not just about fun. Some of my best games or movies, I won't describe them as fun.... The story, the world, the choices I have to make are not necessarily fun.
It's about the quality of the experience in the game, if the game is a horror game, is it a good one? Certainly your word to describe rule of rose or silent hill is not fun, but tense, scared, heart racing, nervous, sweaty.... The best games are those who go beyond just stomping mushrooms and only cater to a younger mindset, but something more involved and less simple.....
I mean people talk of fun fun gun, but for how long will I play wackamole before it stops being both fun and entertaining, I need something diverse and deep to keep me engaged, for much longer....
Which brings me to an issue I see with many gamers these days. A game can't be fun or rather I'd like to use the word engaging, unless it's a hand holding session...... Go to the blinking red point on the map, do an activity like destroy a tower or power an generator, then loop over to the next blinking light and checkpoint..... Anytime you have to think a bit, anytime devs make game mechanics a bit more involved, anytime there's a little challenge involved in the way the game is played, people have a huge problem with that, as if you should just sprint across the world, phase shift across the map in every game.
I still remember how much noise gamers made about not having rewind in a racing Sim some years ago, or not having a big colorful driving line or not allowing them all assists in a motorsports race.... We are so used to games which are built for dummies, which is the only way we qualify fun in our games these days..... In essence fun games are actually simple and uncomplicated, but with simple games they also lack depth and can become quite monotonous.
So, in the last year, you had people saying..... certain games were fun, but they were panned..... "I'm having fun though, but for how will you be engaged if the experience is not that memorable, challenging or if it does not evoke a wider span of emotions from you.....
When gamers say" is it fun" , they mean, can you blow stuff up or some buildings, let's kill lots of zombies or pirates, let's stomp on some mushrooms over and over.... It may be fun for a while, but these are not the best experiences you will get in gaming, if such simple repetitive actions are their only hook. Games which engage the player on a wider range of emotions are almost always the best games.....
In essence, games are much more than fun, games are about the experience and moreso how much engagement you can get out of a player, how much you can stimulate and tittilate their faculties, reflexes etc.....