If I had to pick any one site as the most amazing one I've ever stumbled on, I'd have to say Dwarf Fortress is the best.
I came across this site about four years ago and showed it to my son. Now, as he approaches 12yo, he is still totally engrossed in delving deeply into this game. Some days he can be found reading the Wiki information learning how to program his own personally designed characters. Some days he is programming our old computer to work out his ideas before he loads them into a particular saved game. Sometimes, he can be heard giggling up a storm at the way his latest fortress plays out.
I never imagined that a game which proudly states as it's motto "losing is fun!" would have such a long lasting and deep ability to intrigue my son so well.
Have a wonderful Fall Holiday Season Everyone! Please feel free to let me know how you like my new site and be sure to come back and visit!