How detailed can I write my love scene to not get 18+?

[SundownKid]

It really depends on what country you're in. In the USA (which follows the ESRB rating system), games with gratuitous violence, blood, guns, etc. are often rated "E" or "T" while games with graphic sex would automatically become "AO" and a commercial "dud". In Japan, games with violence from the West are often rated "AO" and barely sell, while games with sex are all over.

I don't think there's a rating system for literature... it tends to be sorted by genre (so young adult would be the equivalent of 13+ Teen rating and the rest would be at the reader's discretion).

Game ratings tend to be far more prudish than books, probably because of the visual depictions in them.

[Ferdokki]

HOLD UP.

I'm reading all these comments about people ranting about US' videogames. How many of you guys have actually played them???
I agree with the way SundownKid described the market here in the US.

Lemme give you small breakdown of stuff per rating, cuz I've played them all (I used to not have a life before college >.<):
* Rated E: Minor "violence", like two characters having a comedic argument or someone hitting someone (but NOT beating them up) for comedic effect.
* Rated E10+: Mild "cartoon" violence, like characters getting run over for comedic effect (no blood/guts shown, possibly bruises though). A weapon or two might be shown (though the game "Shadow the Hedgehog" which had a E10+ rating, was heavily criticized for incorporating a machine gun used to kill aliens/machiens, and it received lower ratings). Some romance can be shown, like implied feelings (a crush), or even a kiss or a romantic hug. Can have mild language (a mild curse word or two like "hell" or "damn", or some sort of comedic threat)
* Rated T: For 13+. Has some violence, like an implied death (blood shown), fighting, or weapon use. A couple of uses of strong language, some crude humor (toilet humor, anatomy jokes, or light sex jokes), and has some sexual content (making out, implied sex).

All the other extreme stuff not listed goes in "M" or "AO", which is a no-no for the stuff Tenshi1 wants to write (heh-heh, sorry for getting off-topic on your thread).
If you're going to imply sex, you could get a rating of T (13+). I know you said you want to create a game for all ages, but if you're going to involve sex, that's not really going to happen.

With that being said, online VN games don't really have videogame rating restrictions. The only restrictions you may face might be from websites that may host/review your game, but reviewers/hosts are pretty gratuitous and still allow the games to be played anyway.
So you shouldn't really have to worry about that sex scene.

As for writing it, you can subtly imply the sex, like maybe the moments leading up to it and stopping before actual penetration or heavy petting occurs. I remember when I was 13 or 14, many books in our school library had implied sex scenes, and the school found it ok for these books to be in the library because they were rated 12+ or 13+. I particularly remember one book that I read in which sex was implied.
The character was a boy, and he said he was comforting a friend (and his crush, who also liked him), and then she started crawling on top of him and kissing him. He was expressing his feelings of passion (like "I really liked the way her lips felt" or something like that) to the reader, and kissed her back (obviously, they were making out). He then went onto say that the girl unbuttoned his pants while he unbuttoned her blouse or took off her shirt or something. The scene stopped there.
In the next scene, the sex was implied to have ended awhile back. The character narrated that he watched the girl put on her clothes (her pants and top, her undergarments were not mentioned) and both of them were worn out. End of sex scene.
(NOTE: The only reason I remember this scene was because it came out of NOWHERE in the book, and I was kinda shocked that it was going on. I'm not a creeper obsessed with lame teenage sex! >.<)

You could do your writing like that. Like, the characters for your game could start off hugging or something and then feeling some "passion" so that they start kissing. You can say something like "They wanted more of each other" or some other transition that implies they will have sex. You can have them go to the bedroom (or whatever, depending on where they're doing it), and then end the scene there. You can have a CG of the two of them lying next to each other, with covers on them or something. Or you could have one of them wake up and talk about how peaceful the other looks and how deeply they're sleeping.
OR, you could continue the scene instead of stopping it. Doing this will mean a bit more "adultness" content is added though. Anyway, again, the characters will go to whatever place they will do the deed. You can then narrate them taking off their clothes (or each other's clothes, whichever you prefer). You can make subtle comments on their body (ex: if a girl is looking at a boy's body, she can say, "His chest is so masculine" or "His abs were so chiseled"; if a boy is looking at a girl's body you can say, "Her body is so beautiful" or "Her skin was radiating" or "Her waist was so curvy". Try not to get too detailed on the female's body description, as, for some reason, people get kinda flustered over female body part descriptions, idk why). You could even go on to narrate light touching, like the girl stroked the boy's chest, or the boy put his hands on the small of the girl's back, etc. And the scene would end there. Again, the scene can start up with the CG aforementioned or by the characters commenting on how the other one looks.

Sorry for the long post, just trying to help. >.<
Hope this gave you some help! =)

[SBG_Eric]

I am not a lawyer.
For the United States of America, I suggest that you follow the guidelines of the Entertainment Software Ratings Board (ESRB). Here's the link http://www.esrb.org/index-js.jsp

For Europe, I suggest you go with the Pan European Game Information (PEGI) guidelines.
Here's a link. http://www.pegi.info/en/index/

Whatever you decide to rate your VN, I suggest you include a content description (such as rated M for brief nudity)

I'll speak from my knowledge as someone from the US:

You are free to "rate", for a lack of better term, your game as you see fit. Keep in mind, if you haven't had the ESRB rate your game then distribution is at the discretion of the distributor. Steam won't, for example, list games with explicit content if they don't have an ESRB certified rating, an expensive and lengthy process.