There isn't anything like that, but you do have access to buyer emails after each purchase, so you could technically send the emails out manually if the purchase volume isn't unreasonably high.
You're looking to send the same template to all purchases per game? What about if the message appeared on the download page? For paid games, the "Download & Install Instructions" only appear to buyers on their download page. (And anyone who has gotten a key). Maybe that works for you?
Maybe the Download & Instructions would work and I agree that low volume individual sales could work (though I'd have to figure out a way to automate). I was more thinking along the lines of - I'm taking preorders (though you could extend to early access), and I'd like to send a "special" thank you to those who take the leap of faith to preorder. I would turn that feature off after the product is in full release (or maybe you'd just change the email). Just looking for a way to send an automated email after purchase. Maybe a feature request to consider for the site.
