The Players Manual- The instructions for actually playing the game should be imbedded within the game via a "help" system. Printed instructions should do little more than list which keys do what or give an overview of the menu system. Help should be context sensitive (when you invoke help, it first brings up a help screen relevant to where the player is in the game.)
Hypertext Historical System- It's increasingly popular to have a context sensitive historical manual built into the system. When invoked, the system brings up historical data relevant to where the player is in the game. The "hypertext" refers to a system whereby key words on the screen are highlighted to serve as a command (when the cursor is placed over them and activated) to pop up another screen relevant to that key word.