Well, this'll be a short one.
I added the basket, and you can put the leaves in it, causing the game to allow you further into the caverns.
Today was the first day when I did a test that went "ok, we'll just pretend we've played the game all the way to the chamber". It was easy, just pre-play the game in a subroutine and return it.
I meant to do the walls today, but I think I'll save that until later. They're funny but kinda special-cased, and I'll need to figure out how to do them.
I'm now convinced that passing callbacks into the game engine the way I'm doing is a bit too powerful. Discussing with jnthn++, I figured out a better, safer way to do it. Will make that change sometime in the next few days, too.