As other have mentioned Valve basically flips a coin and depending on how deep the rabbit whole you want to go... (I won't get too much into it), you will see that at times they let "tame" games on the store front but yet GOG bans them or Valve just bans the game all together. Valve will flip flop and say the game is okay and then say it's banned only to later allow it after the devs changed an image. The only part that Valve does seem to be consistent on is games that Nintendo and Sony have allowed so if Nintendo and Sony of Japan have let their games be a certain ways in those region but yet the western Sony or Nintendo branches want it censored, Valve will allow it to remain in it's original form, but since a lot of these VNs don't have console releases then Valve basically flips a coin.
There is the whole school girl thing as well which Valve always gives very vague comments about and that is usually associated with VNs
There is the whole school girl thing as well which Valve always gives very vague comments about and that is usually associated with VNs