And I should clarify, when I said I don't want to overextend myself, it was referring to the fact that the story would take place across a multitude of environments/various characters, motivations and multiple routes that just expanded enormously and overwhelmed me.
It need a good preparation, and
a little bit of knowledge.
How to do it, especially regarding the preparation, depend on you, because everyone have its own way to see thing and some methods would works better for them than others.
Personally I would recommend to write most of the script (in the movie meaning of the word, so not the code) before your starts the game. No need to goes on the detail and actually have all the dialog lines, but enough to know what is happening in each scene, as well as when and how the variations take place. You starts by writing the script straight as if it was a purely kinetic novel without choices, then you goes back at it and add the choices and variations to your script. For the variations, either you do all at once, or you focus on a character. The later need more times, but can possibly be more efficient. And finally, you goes on your script a last time, to harmonize all this.
Personally I found this better because you're always in control. At first you're only working on a linear story, so you don't have to care about the choices and variations, just about the story and what happen there.
Then, when you've the whole story, you can add the choices and variations. And this time you still can focus on only one topic, since you already know where the story is going and, therefore, what will happen next.
As I said, it need more time, way more time. But in the same time it's less overwhelming. And, more important, it lead to a fully coherent result. Having the main story already defined when you add the variations, you'll quickly see if adding "that choice" at "that place" make sense or not.
There's a game I don't remember the name, where you've the possibility to submit to a girl... and then will not see her for something like two in game months, this while still having a lot of interactions with other girls. I don't remember precisely the reason, a long holiday or something like that, but it really looks ridiculous. And, while no example cross my mind, there's surely more than one example where a choice absolutely not fit with the rest of the story, like by example hitting the gym to impress a girl, then later having your ass kicked by a toddler.
Like I said, my programming skills are definitely not up to par with even your example (And I'm a very slow learned, I need to do it over and over until I grasp simple concepts in programming for example). But I will try it! Thank you!
I wasn't, and still aren't, trying to force you on your original idea. I think that you made the right choice by deciding to starts with something smaller. There's way more being making a game that coding. So, unless you've prior experience, starting with a smaller project permit to slowly assimilate this, while experiencing all the works it imply.
It was more, hmm, let's call this "motivation boost"; some kind of "don't be afraid, it looks scaring but isn't this difficult". This with in the same time an example that you can already use as base for your smaller game. Something that would give you some practice and make this easier to envision when you'll starts your big idea.
1. Any recommendations for planning software to use for storyboarding or should I just keep using Excel?
It's parts of what depend on you.
It's like when you studied for a test at school. Some learn better by writing down the important points, some need to read everything out aloud, and some just need a quick reading right before test. Saying that "this works", or that "this is better", would be misleading here. You could end with something that absolutely not fit you, struggling with it and believing that you are no good, while in fact the problem is the method that isn't for you.
2. Any idea how to add a scrollable high-resolution image on top of the current scene image similar to how Midnight Paradise does?
As you found yourself, a screen with a viewport displayed on top of the image is a way to do it.
There's other way, but it's probably the most practicable because you can size the viewport and so continue to see a part of the image behind.
Dark magic for now, will twinkle with it until I understand the ins and outs.
It's the way to go, and this for everyone.
Even me I mostly do like this. My decades of coding experience make that I probably have a better understanding of the doc, but nothing beat a practical test to really understand something and/or make the particularity stick in your mind.