Playing Tetris on the GameBoy, there are no instructions telling you what to do. Nor do they tell you what to do. I do not have access the original box, and what have you, to learn if that’s All There in the Manual.
However, regardless, there are a few fundamental differences between playing that on the GameBoy and playing a game using the keyboard. Firstly, how do you know you’re not supposed to be using the mouse? Secondly there are loads of buttons on the keyboard, surely at least 25 compared to the 8 on me SP. Thirdly, the conventions are less set in stone on the keyboard compared to the GameBoy where you can only use the only possibility is the arrows for four(or three)-directional movement.
A second thing that interests me is what is the goal of Mode B? I suppose the existence of a highscore table implies that its to get as high on that as possible, but I know that I don’t care even slightly about my score on it. The only interest is in completing the 25 lines to get the, far far too long, winning animation. I am more likely to set myself challenges like singles-only than focusing on getting the top score. Indeed, nowadays you would probably get an achievement for that, and would the goal of the game be to collect the achievements, maximise your score, or simply complete all, twenty-five. Should you let the player decide, or put it All There in the Manual?
However, how far – even without a manual – can the player decide freely, rather than deciding to agree or disagree with the game? In Mode A, I used to play to maximise the number of lines I got; sometime I still do. However, it is clear that the game feels that you ought to be getting the highest possible score to get an ever-larger missile. The game can speak or itself when it comes to the goal, just like the game speaks for itself by acting in response to the trial-and-erroring player hitting keys.
Ultimately, therefore all the good that can come from putting it All There in the Manual is that it can save the player time. On the other hand, the feel of exploration that would be reduced by reading he manual is quite a good one. A negative point, is that the existence of a manual puts a point where dissonance can exist with the game; what if the manual said Mode A was all about maximising the number of lines? On the other hand, that might be what you’re after.