Yeah, you seem WAAAAAAAYYYYY too wrapped up in giving out some sort of prize. If you don't think you can make it interesting, it'll come through, and that's exactly what you sound like right now. "I think they'll dismiss me so I want something to bribe them with for their attention".
Figure out some way to tie your job into computer games, MAME if you so desire, and go with it. Kids KNOW computer games. What they won't know is what might go into that game, the thing you want to talk about.