Thanks for the heads-up and the instructions, Neemys!

Thanks Phillip_Lynx - that's good news!

tl;dr: can I undo my decision to purchase via Steam?

A long time ago I played DOTA2 for about 5 minutes, which required setting up steam. When I saw Factorio I knew this was a game I should avoid for fear of never having free time again. I failed, and decided to grab it from Steam as it seemed easy ...