Just a BTW anecdote. The last school I taught at before retiring 30 years ago, used to have an "activities week" at the ends of terms, in which the timetable was suspended and each member of staff offered an activity which pupils could choose among. I did a crossword week once. Photocopied Times puzzles, & we would each have a copy & solve them together -- about 25 in the group. There was some correlation between top set pupils and cruciverbal ability; but not entirely so. A few years later, I met the overall most brilliant pupil from that crossword group, but who had not been all that outstanding at the puzzles, while she was studying at Cambridge after 6th-form college. We chatted of this & that. "I remember your crossword group," she told me. "I opted for it to see if I could learn to cope with them. But I still can't do them!"
Even so, she went on to first in maths from Cambridge...

Another educationally useful game BTW could be Yahtze. But as to whether such games should be parts of the regular curriculum, as the thread topic suggests, or retain their freshness by remaining interesting leisure activities as Joe pleads above 0915AM...