So what would you advise? Are you calling for the game to be banned? Or is it simply a moral argument you're making? If the latter, then many would agree with you that it is, at the best, morally questionable to make a game like RapeLay. If the former...well, bans aren't really practicable, especially once you get people's back up about it--there would simply be a black market for illegal hentai games, much as there is now for child porn.
One thing that works but has been largely neglected is exposure. Prohibition does not really work, unless we talk about fascism. So, what is needed here is exposure to the media. Let the media talk about it, analyze it, display it, and let the people know that this game exists. Then if public opinion is largely against it, the company that made the game will be largely stigmatized and driven out of business in the most natural manner.
I don't think allowing a game like this one suggests that society is accepting rape any more than games with theft say that society accepts theft or games with murder say that society accepts murder or games with war say that society accepts war.
You can't stick everything in the same bag. There is a reason why you are stealing and from who you are stealing or who you are killing. As I said above, defense = good, offense = bad. So, if the poverty is so great and few people are ultra rich and you steal from them in order to feed your children, that's defense. It can be accepted. If you kill an oppressive dictator, that's defense, and it is acceptable. If you steal a kid's launch money, that's offense, and it's not acceptable. If you murder someone because you wanted to steal his watch, then that's offense, and it's not acceptable.
Rape, by it's very definition, is a violation of the other people's rights. It's offensive, and therefore not acceptable. By allowing this game to exist, society winks to people that "hey, it may be officially wrong, but in reality it is not that wrong".
Another viewpoint is the victim's viewpoint. If you would have been raped, how would you feel that your pain has become the object of entertainment for some people, and most importantly, how would you feel that society largely ignores your pain and instead tries to profit from it? if not betrayed, then you would feel raped again, at least psychologically.
Is it really worthwhile for a society to ignore victims in favor of entertainment? isn't it a moral downhill that one person's pain becomes the entertainment of another person, and that is accepted by the rest of the people? isn't that a violation of human rights?