At my school, like many others we have a unit of work in Year 7 Technology Mandatory on Game Design. We’ve dabbled with Microsofts free Kodu (maybe Project Spark in the future) but mostly we have been using an older version of YoYo Games Gamemaker, you can grab a legacy version for free from this site.
The kids really engage with Video Game Design as it’s such a strong influence on their generation. One of the areas that create some disengagement for some students can be with the creative side, making good looking assets (graphics). Well a company called Tiny Speck has just released the assets from their now defunct game called Glitch into the public domain, meaning anyone can play around with their professionally crafted designs. For me it means that I can grab the spritesheets and let kids loose, seeing what they can come up with.
Mr Sully's Blog 