I'm not really sure but all I can say that this game was on humble bundle for a week (pre-order only) so maybe there were some people waiting to buy the game

There was a promotion called Wishlist Quest and there were 100 copies being given away. Yes.

There was a promotion by the devs. If you wishlist it on Steam, screencap it, and send it to them, you could have won a copy of it.
I think that's it. if I'm not wrong.
The promotion is over now anyway.

To clarify further: there was a promotional deal run by the devs involving wish listing this game and sending them a screencap via a google form, they had reward tiers including their previous game, it's soundtrack and art book, as well as the soundtrack and art book for this game (Omensight). Simultaneously, of the participants 100 were randomly also given keys to this game.

they said that for the soundtrack for omensight and that they had a separate e-mail to give the winners this while everyone in wishlist quest got game/OST/Artbook for path of destinies.