Like a simplification that doesn't account for friction? 

There was a guy named Enkeli who knew how to do that for AOE II.   https://www.indiegogo.com/es/projects/enkelikuoleman/rise-of-kings-medieval-warfare He knows how to convert 3D models to Sprite models.

I see. I wonder if increasing on-center repulsion range (to leave free self-alignment rotation) could have been a way out of that. Btw, I noticed that in your code you mention "a circular body is always struck through its centre", I guess this is some non-physical simplification since you might care more about just rotating elongated objects?

If you've ever played with the militia in AoE III, you'll know that they're only there to raise a defense army very quickly and they die easily. It's the same here. https://ageofempires.fandom.com/wiki/Militiaman  

not sure if it is finished or ready, but it might be a good idea to implement some way for animations to play depending on motion at the time of death.