Selecting genre is not generally crucial to the telling of a story, though certainly story creators may have a favourite genre they like creating within. However, within computer-mediated storytelling genre becomes useful for a number of reasons.

First, certain genres lend themselves well to certain types of computer based stories. For instance, if the theme is "crime never pays", then it is useful to know that the choice of mystery genre fits nicely into the digital story shape of sequential sets. The audience is motivated to interactively explore a landscape through their avatar, in order to find the clues to solve a crime. Having a certain number of significant clues means that the audience is ready to be introduced to a new stage of the story where another set of clues may be found, etc. until the audience, through their avatar, can point to whodunnit. Under a Killing Moon [Acc94] is structured in this manner.

Another consideration is that genres use a certain shorthand because it is expected that the audience is familiar with the conventions of that genre. This means that certain leaps of logic can be safely made in connecting pieces of a story together, since it is understood what is likely to have occurred between the scenes. In a romance if our hero comes bursting into the ingenue's bedroom such that she grabs the bed curtains and clutches them tightly around herself, after an exchange between them, should the ingenue release the bed curtains and the scene changes, then the audience can safely presume that sex was had.

Also, given the genre as well as the theme, certain available choices for the audience are going to make more sense than others. If our theme is true love is found in recognising people's inner qualities, then again the genre of romance may be chosen and at some juncture an ingenue may need to choose between the devastatingly handsome but shifty Eric, or the geeky but loving and honourable George. To add to these choices that the ingenue may choose to ditch the two of them and go for an ice cream would be a change in both genre and theme.