Thanks for sharing! Looks like some solid work has been happening.
Actually, based on what he wrote here and depending on the implementation, he did a lot of work to iron out some issue I identified with the second prologue release, and implemented quite a few systems that could have taken a while to script/code-especially if they are truly responsive/dynamic and tie into other variables in a meaningful way. IF--and this is a big IF--he established templates that can be reutilized for future parts of the game, and he is as focused as implied in this post, then he could have done a lot of work to set up for much faster future releases due to having a strong script/code base to work from.
Snats has oversold some things in the past, but based on some of the previews over the last three years, he's been working on some ambitious systems that I frankly wasn't sure if he had the chops to implement. If he succeeded, then he deserves a ton of credit for increasing his skills in Ren'Py, especially if he did so without hiring a professional scripter, even more so if he learned actual Python code and not just Ren'Py scripting.
Something I really zeroed in on is the layered images. He experimented with layers and masking, and frankly I feel those tend to fall flat and remove a lot of the immersion and depth that you want from a visual novel. Masking is fine if done correctly (however, he did run into minor alignment issues that I've pointed out in the past), but layered sprites tend to create dissonance between the characters and their environment, especially if you don't work to maintain the proper depth, lighting, and perspectives relative to the characters' surroundings. He stepped away from that for the last release; I think to positive effect. If he was able to completely remove layering and still end up with a fast, efficient, scene framing and rendering process, then that would be great for the future visual fidelity of the game.
Looking forward to the release, and if it's as good as it has the potential to be, I might consider supporting him for the first time ever, as it proves that he's not only working hard, but working smart on the game in a way that he hasn't since even the old version.