I would have to say things like playing marbles or even conkers, to be honest. I remember when I was a kid we used to go through a phase when conkers were falling from the trees where we would put them on the string and play conkers with one another in school but that seemed to phase out and you never hear of it anymore.
Marbles is another. I always remember my friends taking marbles to school and playing with friends and now you don't hardly hear of people playing marbles.