Your image is as much a "per frame animation" as those in game. If you pay attention to the animations in game they are multi layered images that are stretched and skewered. take the
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for example.
Now I'm about to get detailed so that are squeamish, prudish are pregnant pleas exit the site and close your browser.
Now that that's out of the way watch as she strokes his erect bonner. The way all the details in the drawing for it stay perfectly regular and uniform. That's not something you would get with a frame by frame drawing.
On the one hand there are details that are to good to be drawn frame by frame, unless your realy good, patient, and have a critical enough eye. With that said on the other hand the animations are not good enough to be frame by frame. There is to much regular and to much irregular movement. Key frames are drawn but the rest is image manipulation.
found a
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of the games scenes. If you pay attention pretty much all of the movement is up, and down, side to side with the occasional rotation, or deformation. All things you can do with software.
Between your work here and DLoMC your well on your way to (if you wanted to) being able to make your own works.