It's the lolis. I played Demons stele hgame which was so peak I was curious if author is going to release it on steam. So I emailed him about that and he said valve responded with listed requirements for girl's apperance which was pretty detailed like promortions of eyes to head or head to a body etc.

It was couple years ago so I imagine their policy has changed for the worse so I doubt we will be seeing nekopara or blue archive on steam since that would mean completely overhauling the char designs.