
My favourite 'toy' was my Scalextric, but there were so many improvised games.
Conkers. We lived in South London, near Wandsworth Common and Clapham Common, and used to pride ourselves on our ability to spot a champion conker. I seem to recall boiling them in water with some vinegar to harden them up, though that was probably considered cheating by some... A 'threesie' was a conker that had defeated three others (by smashing them to smithereens!).
Flicksy. You would stand a line of playing cards against a wall and flick other card at them - a sort of card version of a coconut shy.
I also remember a game with a dart with my mate Ian that involved throwing the dart between your opponent's feet. That ended when I inevitably got a dart stuck in my foot.
Marbles. For the life of me I can't remember what we did with the damn things, though I'm sure it involved something destructive.
Cowboys and Indians. No explanation required...
Cops 'n robbers. Ditto
Many more, I'm sure, but they escape me for now.