For the yanks and elsewhere, yes conkers is well known in Britain. You basically put a chestnut (but its a conker) on a string by making a hole in the middle. Take turns swinging them on the string, whoever's breaks is the loser.
It used to be great fun till it was banned/requires eye protection now. There's an opportunity there, someone could make a perfectly safe conker app. I'm sure that would adequately replace it. /s
Because I can’t see how authorities could ban anyone from picking up a conker from the ground and tying a string to it.
On a different note, if you’re just pulling a random one out of a bag, what is the competitive aspect? Is there a technique involved? Or just RNG?
Believe it or not adults playing conkers or people playing conkers outside of schools isn't a common pass time.
It is pretty much RNG, though you can massively nerf a conkers structural integrity by making the hole through the middle poorly, so there are some techniques. People also used to use thicker shoelaces like in vans, which I think made the centre more solid. I've never run an experiment to verify the difference that might make.
I also hope you see the irony of your ways.