How about recreational activity, board game, or hobby?
Chess is a sport, science or art?

No, this question has to be objective. We can't be content by just saying it is our preference to call it a sport or not. That would lose all obsession with the question and we would just use that answer for everything.
1. If a tree falls in the forest and no one is there, does it make a sound? Depends on the person if they want to believe it does.
2. Should you lower the toilet seat after peeing? Depends on the person if they want to believe it should be lowered.
3. Should we use chopsticks or fork and knife when ordering Chinese food? Depends on the person if they want to use chopsticks or fork and knife.
etc....
For me its three of this, and I don’t know if actually someone can add another category for Chess