Sometimes I take it for granted that some people will use all of the information available to them when they learn how to play a game, but they don't. Most people like to jump in and start going full-bore. Sometimes, that's fine, and you can learn all the gameplay you need to be moderately successful by ham-handedly jumping in and wailing on the buttons, hoping they do something useful.
But you can do it a little more quickly. Take Q*bert, for example. Let the game sit there with no money in it and you'll see some screens that teach you how to play the game.
That screen succinctly describes everything you need to know about how to play the game.
Now, I fully realize that most games nowadays are an eensy bit more complicated than Q*bert, so they come with manuals that are upwards of a dozen pages in some cases (a dozen pages smaller than a 3x5 index card, even). But you'd be amazed what the developers put in there. It's almost like they want you to know how to play their game and give you a handy pocket-sized reference.
Shocking!