The list typically updates once every month or so (usually a few months go by between updates at the moment). It updates a little more often when a new story is coming out. There are also discounts and goodies only available for the mailing list. If there’s a discount going on, it will show up in the welcome email when you subscribe.
Already on the list, or want to download Asher without joining the mailing list? Link pending while I put it up on Itch.io. (Mediafire link here, in the meantime).