ばか！バカ！　馬鹿ー月！

I don't know if it is a stupid question, but i really can't find an answer on my own.

Translating a LN from English to Italian, i found the sentence : 'R15, which means it can only be bought by those 15 and up, Galge'. I did a google's search to find what is a Galge game, and i found that they intend a general avatar gameplay, where you live an adventure in first-view perspective, just like ace attorney's saga. Ok right here, but then, why are they forbidden to under 15? Although Wikipedia says there is an hentai subgenre of it, in general, if it is what i think, a Galge is not an hot or sexual kind of game, so it should be OK for under 15 too (it would be the same reasoning of 'because there are hentai mangas, then all the mangas are to be forbidden to under 15').
Maybe i did not understand what a Galge in reality is?

I know, it's not important for the translation, but the question puzzles me.

Galge = Gal Game = Dating Sim = Dating Simulation

There are Non-H and H (Eroge) versions of them, although someone who played them would give you more details.

@raffreddato: Misogi sums it up pretty nicely.. if you would like further reading, here's a more detailed explanation on the subject matter, though it covers Visual Novels (VNs) in general..

Understood! thanks for your answers