So I was reading "A Theory of Fun for Game Designers" and one idea particularly resonated with me. Idea is: "Games are like story generators".
The book elaborated on the distinction between "stories" and "games". If you take, say, a book, the story is there on purpose and you consume it by reading. Most computer games (the non-abstract ones) have their storylines, and - in similar manner - you learn the story by playing. That's not what I mean. This is not "story generation" because the story is sort of already there. Non-abstract games tend to be like movies and books in this regard, even if the story branches off into different variants in predefined monents. The best stuff happens when it's not the game designer, but the game and the player who create the story together.