Thanks for playing!
Yeah, I only managed to make content up to the boss (Gust), so you've seen everything there is to see. The bit where you fall into oblivion is indeed the correct next place to go, but I hadn't made anything and forgot to block it off. I also stupidly didn't put in a screen that notes that you've reached the end. I added a note in the description, but you don't need to go to the game page to download, so I suspect a lot of people have / will miss it.
As for the controls: I may need to rethink that. I modeled it off Super Smash Bros.'s up special attack, because the ultimate goal was to have the move be an upwards attack in addition to just a jump (though the current implementation is just a jump), so I wanted you to be able to do it without needing to jump first. I think it's easier to do on a controller, and shift is maybe not a great button for my purposes for keyboard controls. I'll have to do some more testing when I make it into the full ability later.
I also didn't get to the complete tutorial I wanted to make, so the fact that you needed to dismantle stuff for research was probably not well explained. But I'm glad you eventually did figure it out!
Anyway, thanks for the review and for playing!