Granted, my coding knowledge is pretty limited compared to actual coders, but with the gameplay in SU isn't it more or less just a slideshow? I mean a powerpoint could be made with the art assets and get the same results. How jank does the sourcecode get with that as the goal?
So, i'll give you an example, basically, imagine like this, a normal person when creating a game like this, would create by hand each scene and calling them when its needed, which is fine when you have in scope like 10 scenes, when you have a X number, we dont do that as a programmer, what we do in these situations were there is "redundancy" when something that is really similar is created N times, we create a "blueprint" or a "factory", imagine a house, a house has one door, two windows and a garage, for example, the blueprint has that, and when you call, you can specify the particularity of those elements, the door is made with wood, the window its going to be a big block of glass etc, and when that house has run its course, which is the scene in this example, the "house" is destroyed, as it has run its course and dont have a purpose, this prevent a lot of problems, the increase in size of the game, load times, possible memory leak and most important, bugs, because if one scene works, every single one will work because they use the same principle, using the example, if you build the house once, and it stands, the door works, you can open the window, basically every single one will work, if you try to create a dog house for example in a different house, but wanting to maintain that structure, you can, but this is another programming concept that isnt worth it to get in to it.
And there are other good practices, PNG case its basically debatable, in a sense of what are your priorities in the game, PNG its a high resolution type of image file, i could recommend SVG or BMP that are way easier on the file size and all, but you lose in quality, because of how the game is, i dont see much of advantage, hell, you can even transform the image in html and render that in the engine if you want to be that type of guy, but i'm not a specialist in image files, i just know these things because of the basics of web dev.
In concept, the game is not "complex", you can see that because he made the game and it works, but the lack of experience and good practices made the code what its and its just not possible now to stop and rework everything in a month, you can see from previous bugs that happened from time to time like certain events not triggering for people, this is a problem that people that work with development, doesnt even need to be "games", has probably encounter something similar to it, i dont want to say that i would know right now what was the problem and were to solve it, i just saw the code and gave it a look, but those problems are preventable with a few good practices when coding, but now its not as simple as, just change this that solves it, now this is not as complex as a calculator, but its basically a human being in a sense of, good part of the code is connected in some way, which would be my personal nightmare, because when there is a problem such as, event from Galatea for example not working, i would narrow down where is the problem making my job way easier, but now the scope is way bigger than it should, thats why what SR7 says for me make sense, but regardless, i dont work with the game, i'm just doing educated guesses with the information presented, for sure there are people here that way more knowledgeable in this topic that could bring better points and even better solutions than me, but for me, for me this is basically trying to pile cards in a tower were when you put one cards at the top, somewhere randomly just fall and because that one fall, another one fall, and because that one fall, well, you get the idea, one day the tower of cards are not going to be able to receive more cards because the domino effect of problems will be way to big to be even worth rebuilding.