I've uploaded my first project to the Scratch website. If you're going to have ago I suggest you enter your age as 2 or you'll be awhile. It's a bit mundane but it got my kids doing some maths homework. Scratch is a fantastic resource for teaching kids how to program. If you have a look around the site you'll see the variety and various levels of technicality of the programs. The ability to publish programs, swap code and collaborate on the website are great features that really add a supportive and motivating force. Would be a great resource for a games creation workshop. Scratch can also interact with sensor boards and motors.

Links:

Scratch was developed by MITs Lifelong Kindergarten
Good overview in ACM
Scratch with Lego WeDo motors and sensors