Lucasfilm's Habitat was the world's first large-scale attempt at an online community with a graphical interface. The 2D virtual world was available on a beta-test basis from 1986 to 1988 through Quantum Link, a dial-up online service for Commodore 64 users. In 1988, a stripped-down version of Habitat, Club Caribe, took its place.
In Habitat, players controlled customizable representations of themselves, which they could see on-screen in a 2D view that resembled early PC adventure games. Avatars could wander a city, visit houses, chat with other players, and buy and sell virtual goods. There was even a virtual in-world newspaper and mail system.
Years after Habitat's demise, its creators authored many papers on the design and implementation of the game and the behavior of its player base. Those papers influenced a new generation of online-world designers whose creations began appearing in the mid-1990s.
Interestingly, one of Habitat's creators coined the modern usage of the term "avatar" in reference to Habitat. Even history's highest-grossing film owes something to this pioneering online world.