Sid Meier's Civilization · MS-DOS · MicroProse · 1991 · Full manual plus an in-game encyclopedia pages
MicroProse shipped a strategy game with a reference encyclopedia — and then built a second one into the game itself, with hyperlinks, years before most people had seen a hyperlink.
Civilization arrived in 1991 as a turn-based strategy game of extraordinary scope, and MicroProse understood that a game spanning six thousand years of human history could not be explained by a quick-reference card. The printed manual is a substantial document, structured as much like a textbook as a rulebook, and it was accompanied by something more unusual: the Civilopedia. The Civilopedia — written by B.C. Milligan, Jeffery L. Briggs and Bruce Shelley — is an in-game encyclopedia presenting the accumulated knowledge of the civilisations the player is building. Crucially, it was navigable by clicking entries to jump to pictures, descriptions and statistics, which is to say it was hypertext, shipped in a commercial DOS game in 1991, several years before the World Wide Web would make that interaction pattern familiar to anyone. A player who wanted to know what Bronze Working actually was, or why Democracy behaved the way it did, could simply click through and find out. The design consequence is significant. Civilization is a game about the relationship between technologies, governments, wonders and units, and the Civilopedia makes that relational structure directly explorable. The manual explains how to play; the Civilopedia explains what the things you are playing with mean.
Shipping a clickable encyclopedia inside a 1991 DOS game
Civilization poses a problem that few games of its era had to face: it is a systems game whose systems are drawn from real history, and the player's enjoyment depends substantially on understanding what those systems represent. Knowing that Bronze Working unlocks Phalanxes is a rule. Knowing what bronze working was, and why it produced heavier infantry, is what makes the rule feel like history rather than arbitrary progression.
The Civilopedia exists to carry that second kind of knowledge, and putting it inside the game rather than only in the box was the crucial call. A manual on the desk is consulted grudgingly. An encyclopedia one click away, while you are actively wondering why your Legion just lost, is consulted constantly — and each consultation deepens the fiction that you are running a civilisation rather than a spreadsheet.
It is worth pausing on the chronology. The Civilopedia shipped in 1991. Tim Berners-Lee's first web page went online that same year, and the web would not be a meaningful part of ordinary computing life for another three or four. The overwhelming majority of Civilization's players in 1991 had never used a hyperlink in their lives, and here was a DOS game presenting them with a cross-referenced, clickable body of knowledge and simply expecting them to work it out.
They did, immediately, because the interaction is intuitive in a way that took the rest of the software industry years to fully internalise. The Civilopedia is a small but genuine piece of evidence that games were experimenting with information architecture well ahead of the mainstream — and it remains a fixture of the series more than thirty years later, largely unchanged in concept.