Oh yeah. Instruction manuals were great. They made it fun to learn all about the characters, items, and controls for the game. And the artwork was usually cool too.
And I'm generally not one for stories in games, but those intro stories that some games had were one of my favorite things in the manuals.
I certainly remember passwords being incorporated in reading material, like the images above. I think Sierra might've done it in some of their games too.
"Shhh! Ben, don't ruin the ending!" --Adrian Ripburger,
Full Throttle