Shadowrun (1st Edition) formed the core of the Shadowrun game system until 1992. It contains a complete history of the future, character generation, archetypes, how to use skills and run combat, magic, computer skills and more.
SHADOWRUN is one of my all time favorite games and this is where it all began. It's harsh, political, and utterly serious about talking about the consequences of 10% of the world dying from plague and another 10% becoming orcs or elves. Cyberpunk Dungeons and Dragons in our world is such a weird premise it's hard to even know where to address it but I think it's still a fascinating world. 1st Edition is where it all began and I think this is probably where everyone should start as the later incarnations of the Sixth World just lack the raw emotion of the first one. The rules are terrible but the world-building is grand and ANGRY at the world. It is pure punk despite its silliness.