I still get goosebumps when I think about the impact that community had on my life.
MUDs tended to be free to play and were run by unix hippies. The line between playing and coders was thin and easily crossed; playing the game led almost inevitably to understanding the mechanics and becoming a coder. I feel sorry for today's generation of gamers, since there is a much larger wall between playing and creating these days. CodeCombat and others are trying to bring that link between gaming and programming back - good for them.