Just played through this game! Really nice :)
I thought I'd mention I found a bug, when holding the key, I walked over to the correct pylon and accidentally dropped it on the ground on the back side of the pylon.
This then caused the key to vanish inside the small rock. And I had to randomly click around until I got lucky and could pick it up again.
Again, great work on the game, hope to see more in the future!