From people who would like to ban/deny this game from steam just name and aestetics would be enough.I'm not really sure if there's actual incest in that game. Like people think one of the two girls you start with is his sister, but the game intro makes it sound like neither girls are actually related.
It is called sister travel , description is " The story of an adventurer and his sister-like companions "
It is same as 1000 year old loli. It does not matter if she is technically adult , Steam or any game rating agency would see her as loli.
And if it really really matter of "incest " , Kagura games or whatever company just need to translate sister as step sister or something .
Personal opinion - in sister travel it was real incest.