@nprofile1q... It seems like a good start.
Though I am curious how I would simulate word of mouth spreading for individual purchases, such as for steam community boosts. In general, it seems for launching sites and subscriptions, games as a service, or ad driven games. This might be a lack of usable data more than method, however.
I'm not sure how relevant this would be to indies making passion projects. But from what I glanced over this seems a better approach than random spreadsheet!