The core conceit here is that of cutting through some vines to allow for an ascent up to the final layer of the map. Ideally this will mean that this section is fairly dynamic; as you cut through vines, you also alter the level geometry! So our vines then must criss cross across the library in interesting ways while also cutting off access to the top.

Here's a sketch showing the two vines, the first in green and the second in orange. There's also a few somewhat incomprehensible lines in blues and yellow to show some possible paths, though for now just focus on the vines. After going down the shaft on the left between the green and orange vines, the player can destroy the green node. This will destroy the green vine and still leave the orange one, which blocks the path further upwards. Then after destroying the orange node the path opens up and the area is complete.

Here we encounter a minor technical challenge; how do we represent the areas for the vines? We could start with a large list of tiles in code represented as a series of x/y coordinates, but that would take up a lot of our available code space. While we certainly don't need to worry too much about code optimization at this point there are almost certainly more efficient ways to deal with this. Luckily, there is a way to mark a series of tiles on the map with zero code that we can use; flags!

Remember flags? Each sprite in the game can have flags. These little circles in the image editor

Right now we're only using a couple of them, flag 0 for spawnable objects and flag 1 for solid walls. If we use flags 2 and 3 for our two vines that'll solve our coding problem very simply. We can just look for all the tiles with flag 2 and put a vine there and do the same for flag 3. We do have one other thing to work around here: we need our flagged tiles to be the library background! But that's easy enough; we can just duplicate the book texture and put it here too. This tradeoff of code comes at the cost of three sprites and two flags, but I think it's worth it.

For the moment I'll leave our big blue 1 and big pink 2 (as well as the blue and pink for where the vines overlap) to make it easy to iterate our vines. With that worked out, here's how it all looks put together:

And there we go! Now we can easily tweak our library level design if we want to without too much hassle. We might want to put an enemy or two in here, and we definitely want some in the hallway leading up to it. This seems like a good time in our development process to focus a bit more on combat, since that's really become the level design bottleneck here. See you next time!