I double checked to remind myself and this is due to Shattered being a ‘pay what you want’ game on itch.io. Due to the way itch’s system works, ANY payment, even $0.01, would entitle someone to a Steam key. I can’t set a minimum payment threshold like I can for the separate ‘paid’ files you can download directly from itch. Because of this the only way to offer Steam keys here would be to also remove the free version and only charge $10 up-front.