Hello and welcome!
Haha, as you can guess from my avatar I am quite the Professor Layton fan.
I have pretty much played all of them, except for the 6th game, Azran Legacy.
I have also written reviews for the first trilogy.
Professor Layton and the Curious Village (DS)
Professor Layton and the Diabolical Box (DS) (In the EU it's Pandora's Box instead of Diabolical Box.)
Professor Layton: and the Unwound Future (DS) (In EU it's known as Lost Future)
I plan on doing reviews for the prequel trilogy sometime future,
but till then those three can give you an idea what the other games are like moralwise.
The Professor Layton series is pretty clean in general,
though I have noticed a few things in the games,
they tend to be rather small however and not frequent,
but they are there never the less.
Also there is a character you meet throughout the series called Granny Riddleton,
she claims to have psychic powers though pretty much all she can do is collect the puzzles you miss.
In Miracle Mask she does sometimes twist her wrist like she is going to cast a spell or something,
nothing happens when she does, but it's annoying never the less.
I am guessing she does it in all the 3DS games that have her.
Though all in all, if I was to compare the Professor Layton games I played to other 3DS games,
I would say the Professor Layton games are a bit cleaner than Pokemon X/Y,
and Legend of Zelda: a Link between Worlds.
Here's some details on the prequel trilogy games.
--The Last Specter (DS) (aka Spectre's Call)--
I think this one would be the cleanest one in the series.
Though there is a bonus game that comes with it called London Life, (which was made by another developer.)
London Life has a fortune teller, but it doesn't go really far in that regard.
(Unfortunately the bonus game London Life, is actually only available in the Japanese and US copies,
I am seriously surprised the EU copies didn't get it. o_O)
Well, Last Specter is a DS game, sooo... onto the 3DS games!
--The Miracle Mask (3DS)--
From memory, I recall a few things...
One character randomly says a line that I would call suggestive. (though it's not directed at a specific gender.)
There are also casinos, but you can't gamble, and gambling is discouraged by the main characters.
Though in the casino area there is a suggestive neon sign,
which is basically an outline of a female holding a cane and is wearing a top hat and what looks like a one piece swimsuit. I don't really recall anything else.
As mentioned, I haven't played Azran Legacy (3DS) yet.
So I really wouldn't know, I doubt it would take a sudden plunge in negative content,
but I guess I just don't know for sure.
As for the 3rd 3DS Professor Layton game...
I actually didn't know there was one... Oh wait,
You mean the crossover Professor Layton vs. Ace Attorney right?
I forgot it was going to be released to the EU soon.
Well, I am not really sure what to think since it's a crossover.
Hopefully this helps, let me know if you have any questions!
Flyleaf wrote:P.S. Excuse my English please. I'm from Germany.

Awesome! I am 50% German myself. (I never actually been Germany though.)
I think your English is great by the way!
