This game, if you look at the scripts and images, you'll see that it isn't made like the others. It's not a static image; it's more like sprites. Those animations are only possible because of that. For example, when Summer is swinging her feet, he didn't create a rendering for each frame. Instead, he took the static scene of Summer and only animated her feet. This might seem like it simplifies rendering, but it makes coding much more complicated.
Speaking of the developer, he removed me from Patreon for sharing the image previews here on the forum.