My personal all time favorite is hands down Halo 2. At that time my family only had dial up and I only ever played Halo 1 or 2 single player. Well one day I make a new friend and stay over at his house and they had high speed internet, Xbox live, and Halo 2. It was the first game I ever played online and it blew my mind. I remember going home and begging my parents for high speed internet and Xbox live but it was a hard sell especially because at the time they didn't mind dial up. They eventually switched after a few months because they got tired of the phone line being tied up lol