I have compiled a list of most egregious problems I've had with the build so far, which I am aiming to fix with this remake.

1️⃣ The inability to launch any scene from the editor.

This is one of the biggest problems I've had while making the game. In order to test a scene, I've had to launch the game from the very beginning. I aim to remove the dependency of separate scenes on the Scene Manager, so that I could launch any scene and work on it. Of course, save game should be loaded as usual.

2️⃣ Not using nodes.

I have a classical programming education; using nodes is still new to me, after all of this time. Which means I'm not using Godot's ingenious resources to their full. I aim to replace many of the abstract objects with nodes that have the same functionality.

3️⃣ Wonky implementation of railroad scenes.

Railroad scenes are scenes where the player doesn't have much control over what is going on. That's the entirety of the tutorial scenes, and many of the story-based scenes that will happen in the middle of the game. My initial mistake was creating railroad scenes first, and then expanding their functionality to include normal scenes. It should've been the other way around; I must've created normal scene functionality first, because they are the standard. Railroad functionality should be an add-on, and that's exactly what I'm aiming to do.

4️⃣ Tiling system.

Hoo boy, you've probably heard so many times about this already. I've been meaning to implement a tiling system for a very very long while now, but haven't had the time. It's either now or never. The reasoning is simple; many backgrounds are huge, spanning thousands upon thousands of pixels, which decreases loading times and has negative impact on the engine performance. By separating backgrounds into tiles, I will vastly improve the game performance and also get a system which allows me to freely reuse assets in different locations.

5️⃣ Saving system.

That's right. When I have first implemented it, I only had two scenes ready. Now that my project's become more complex, there are more and more things to remember, and the current saving system isn't handling it well. I either need to overhaul it or somehow enhance it.
That's it for now. I'm not sure in which order I'll be tackling these issues, but we'll see! For now, I'm transferring all resources from the old project to the new one, and re-doing the folder structure.

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I decided to tackle the tiling first. I must admit, after getting used to it, it's amazing.
The look is vastly different from what I've been making earlier, but overall it looks much more organized and polished. And making locations is SO EASY.
Here are a few screenshots.
Of course there's a lot of work to be done here, but the overall improvement is stunning already.