Further confirmation is provided by the selection of games on offer - a selection that also provides some pretty startling insights into the genre.
There are currently some 50-odd titles available in translation at the moment. Picking titles at random demonstrates pretty clearly that even this limited selection of hentai games caters to the broadest extremes of sexual proclivity: there's transexuality (Yin-Yang - X-Change Alternative); gothic horror (Animamundi - Dark Alchemist); historical romance (Enzai - Falsely Accused); human sacrifice (Bible Black: The Game); submission (Absolute Obedience - Zettai Fukuju Meirei); mild incest (Hitomi - My Stepsister) and much, much more.
And if, for some reason you're stuck without a Windows-compatible PC, you can pick from a choice of interactive DVDs, which all play in a regular DVD player.
And if for some reason you're stuck without a pair of hands, you can chose those games that include a 'hands-free' mode (whatever that means).
And talking of hands, the next part of our research obviously demanded a more hands-on approach. And received, although only one of them in plain cover, presumably because only one of them - Casual Romance Club - was adorned with 12 pictures of naked girls on the box.
Saving that for last, the first game to be subjected to the sort of rigorous scrutiny that you've come to expect from Eurogamer was Critical Point.
Originally released in 2002, the game is essentially a choose-your-own adventure with 24 different paths scripted by Mobile Suit Gundam scriptwriter, Kenichi Matsuzaki.
It's illustrated by partially-animated and still images, and accompanied by a sort of lounge bar jazz soundtrack.
Rather helpfully it can be played in an easily alt-tabbed window, and for anyone who isn't a fan of Matsuzaki-san's work, the game's creators have helpfully included a 'quick' mode, which speeds through the story so fast you don't have to read it.
What a brilliant sales pitch: "Feeling lonely and bored? Now, Play-Asia is making them easily available to us European lot. Is there any more to this heady blend of anime, videogames and porn than antique game mechanics and mildly titillating drawings? The first part of our research took us to Play-Asia's selection of Hentai Games.
Well then, the email went on, why not check out some newly available English-translated Japanese Adult Dating Games? Up until now, if you wanted to feed your Hentai videogame fix you'd have to brush up on your kanji and search out seedy game stores in the side streets of Akihabara. In recent years, companies such as Peach Princess and JAST USA have been making English-language eroge (as it's also known) available to American gamers.