One of the opportunities of digital fiction is to mimic a format or context as a way of implicitly commenting on it. This is one of powers of using software to tell stories, apart from the more obvious affordances of branching plots, embedded video, etc.: it can imitate other software in a way that goes a step beyond a paper book’s ability to recreate a text message thread or PowerPoint deck. It’s the mimetic power of film, brought into the service of literature.
Un/tied (which is actually memoir rather than fiction) does this particularly well. Especially that initial choice on the homepage—an e-commerce sight so common that it’s easy to forget about, but that silently signals theme in the same way as the first shot of a well-made movie.