To put it simply, Dungeons and Dragons reinvented the use of the imagination as a kid's best toy. The cliche of parents waxing nostalgic for their wooden toys and things "they had to make themselves" has now become my own. Looking around at my toddler's room full of trucks, trains, and Transformers, I want to cry out, "I created worlds with nothing more than a twenty-sided die!"
I was just about to link that... 
