(Chibis by Simon Adventure)
Sword Daughter is now available on Steam!
The game includes all your typical steam-powered bells and whistles, like trading cards, collectible backgrounds, and achievements. (If you already own the game, you will need to play through it again to unlock most of the achievements, but this should be easy enough to do with the section map.)
Speaking of which, if you bought the game direct from my website and want a Steam key, please email me with your order information and I'll happily hand one over. Please do ask by email rather than by forums, it makes it so much easier to keep my key list organised.