Quake, released in 1996, was one of the first games to really have internet play as a substantial part of it. From the demo release, there was far more internet play, then single player play. It also had a big effect when id Software released "QuakeC", the code that actually determined the gameplay itself, and gave players the means to edit this code, and change the way the game played. It gave way to a large number of "mods", modifications as to how it's played, and the goal. There is still a substantial crowd of people playing Quake over the internet.
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