I was talking to our IT guy at work today and he'd never heard of it!
I used to love it though, as a child. We never had a home computer, but my Dad was a Headmaster and used to bring one home from school in the holidays for us to use. I used to jump like mad when the witch jumped out!
Tell me I'm not alone?
http://www.4mation.co.uk/retro/retrogranny.html