In most video games or digital narratives, the story is provided to you as part of the experience. Some games, like Dys4ia, are specifically geared toward telling a story as their entire purpose.
But in some cases, you only have the digital environment to work with, and often, that environment gives you only a context, and no particular narrative.
This is where a lot of classic game stories come from. For instance:
Save the princess!
And, um… save the princess!