Why is Fortnite so popular with children and adults?

Why is Fortnite so popular with children and adults?

Free
the genre is popular

You get recognition.

And the gms build the game so that there's no end.

Say who stays here is the recognized professional and everyone wants recognition that would be in a good bowler nothing else.

I would say that it is popular because it is simply childish, but also a big map with lurking different places, then there are two points:

Because of the childlike style, kids CAN ever play it
With the permanent new Seasens always new places come to it, and no place looks like the other!
And it's FREE!

This is of course only my own opinion and respect each other.