Regarding the original Civ manual referenced above. . .
That was back in the Microprose era. Microprose manuals were the best. You bought M1 Tank Platoon and you got a long, detailed manual where at least one third of it was context and detailed explanations of doctrine and real-world specs. Followed by twenty pages of "designer notes" where you could read about how and why things worked the way they did. . . and what their hopes, goals, and dreams for the game were. . . and how they made it (or didn't) into the final product.
Silent Service. . . same thing. . . wonderful historical information, etc.
Perhaps the only company that rivaled Microsoft where game manuals were concerned was Lucasarts. Their "Their Finest Hour: The Battle of Britain" game had the best manual I've ever seen. Chapter after chapter on the history of the battle and day-by-day accounts even. With photos. It put my Time-Life book on the subject (and some real history texts I've since seen) to shame.
Origin also did nice manuals for the Ultima series. Especially Ultima IV. Seperate spell book and book of lore. All done in full prose. And they didn't break suspension of disbelief.
H
LucasArts made the best manuals, period. I still have my complete TIE Fighter game box, 3.5" disks, reference card, registration card, and the Pilot's Manual.
The manual is outstanding --- I've read it several times over. Not only does it include detailed analysis of the game itself, it also includes in-depth info on all of the spacecraft, and after that, it includes are novel. A novel.
And a damn good novel, at that. I've read it three times over, and I still love it.