Thanks for noticing! And
there is an OT.
The game can be purchased for 15$
on the Humble Store, but there is no information about any Steam key then, only about a DRM-free version. However, the HS usually provides Steam keys when the game is released. If you pay on the HS though, you have immediate access to the game.
I have to say I have finished the game with about half of the collectibles and it is original enough to be enjoyable.
And if you are interested in this information, the game will have a picture for the grid view of your Steam library. These are pictures from the Steam store.