Well you have to be a 'character'. Something they can identify with.
Like....I don't know, maybe you're the guy that can pull funny faces or tell really bad jokes or maybe you have a skill they can link to you. Drawing; playing football; making funny noises....
I've worked with children for thirty odd years. And had three of my own. They go through different stages.
When they're babes they just like to feel close to you. When they're pre-school their world is fascinating ! Everything from drawing to listening to stories to noises....it's endless ! Once at school they get told 'facts'. How the 'real' world works ! So it's stuff like.....Dinosaurs ! Animals ! Volcanoes ! At Junior(High) school they're doing things independently and are learning 'gameplay' either electronically or in terms of team games. And as teens......yeah well good luck with that one !