I'm running a day for 30 kids aged 11-18 about computer game programming. They have all opted to do it, but they have no experience at all of programming. My main aim is for them to learn a few things:

• programming is hard/challenging
• programming is something they can learn to do
• being a computer games programmer != playing games all day
• a little more insight into how games actually work

I'd thought of splitting them into two groups, of younger/less experience and older/more experience, then doing slightly different things.

I'd considered showing them Scratch, Game Maker, before showing them the basics of Python and getting them to write a simple text based game (perhaps something like, computer picks a random number, you have to guess it in as few guesses as possible, computer says higher/lower for each guess).

Does anyone have any ideas of things to do/show them/ways to teach them?