I ran a Minecraft server for a couple of years (2012-2014) for
   my nephew, who was 7 at the time and really wanted me to. I did
   it, it got popular - total of 27,000 unique visitors and lots of
   dedicated people playing. All creative with a little survival. I
   was sad when it was killing my poor laptop and I had to shut it
   down, but I kept ALL of their creations and promised them that
   SOMEDAY I'd get their creations to them. I feel like the dad in
   the Lego Movie sometimes because of it but... my poor laptop
   just wasn't designed for such heavy duty 24 hr service* :) It
   was an awesome experience. The things these kids/teens/adults
   create on Minecraft are amazing beyond belief. I still go on the
   LAN with my nephew (he's 10 now) from time to time and do stuff
   with him. It's a blast.