In a way, I feel like developing an engine like that in Scratch is more of a masochistic art than a practical avenue for creating something in-depth. Scratch was sort of designed for games with less complex logic than platformer physics. It can be fun to do things like this in Scratch "just to show that it can be done," but as we can see from the screenshot, it gets kind of convoluted, and at a certain point, creating this kind of thing in Scratch becomes much harder and less straightforward than when using tools like Game Maker that were more directly intended for this type of development.