At the beginning of each game project there is a prototyping phase. Prototypes help teams to agree on a vision, to have something concrete to discuss. Deciding what goes into a prototype is a matter of experience and, I would say, an art in itself!
In most cases, an exciting idea leads a group of people to want to quickly create something well done. The final prototype then focuses on proving a thesis.
I believe that a football game where the players are books works: we immediately create the typical mechanics of a football game and, instead of the players, we put books on it. It will be awesome.
There are also cases in which a prototype serves to demonstrate what is wrong with the idea. Some skilled designers manage to use prototypes to undermine their assumptions. It is a work of self-criticism, of searching for weak points. It rarely happens in companies, but it happens in independent projects. And it may lead to something truly unique.
Returning to the example, I believe that a football game where the players are the books works. I created a prototype centred on how silly this concept of books playing football is. I don't devote myself to creating the mechanics of a soccer game, I am dedicated to creating the nastiest version of a book by running with a ball.
And very often, magic happens!
Whichever method you use, the important thing is to establish clear and measurable objectives, and be ready to discard the prototypes if they have not all been satisfied.
I assure you that more than one frustration is avoided!