With a few exceptions (Life is Strange, Oxenfree), it seems like there simply isn't any attempts for games to pierce the young adult market. I find this not only odd, but problematic; I'll outline a few reasons why.

First: as seen with books and (to a degree) movies, the young adult market is lucrative if the media in question is done right; This is evident in the level of notability that many books (and again) movies have. Maze Runner, Hunger Games, Maximum Ride.... The list goes on. The question is why hasn't there been a game that has targeted the YA market? The market is lucrative, almost as much as the pure adult market, and being hit-or-miss with quality has never deterred creators and their crews in the past. It just seems ludicrous to me that the YA market hasn't yet become a major target for the game industry.

Second: (thought this is less important) Maturing as a medium requires the industry to approach controversial topics in a sensible manner. This is something the Industry has a bad track record of (though said track record is, admittedly, overblown) and while it is getting better, there is a way to speed up the process without causing further aggravation to the critics. Games are often considered toys for adults, and this stigma is severely limiting for the industry's creative processes.

Third: Most T-rated games that originate in the US are basically M-rated games with less gore, violence, and sex. This is probably the least important of my concerns, though.

As I mentioned, this untapped market could potentially be a commercially lucrative and creatively liberating experience for the industry as a whole, yet it seems that the lack of a disposable income effectively limits the degree to which games can target that market, despite it's benefits.

So therein comes the question: Why hasn't there been a game that is aimed towards young adults? Is it for the reasons that I have outlined, or are there other reasons that the industry hasn't targeted that market yet?

If my list wasn't comprehensive, I'd like further replies that outline other reasons as to why there are no YA games.

I was under the impression that about half the AAA out there were for young adults (if not more!)...

As an adult, I struggle to find products tailored to my need, and oftentimes find myself faced with artificially regressed products with characters that clearly depict younger protagonists than I wish it would. I was very happy to see The Witcher III succeed because I felt it was the first protagonist over 30 to actually make sense in a long time!

I think we have a radically different definition of what a young adult game actually is, and here might lie the issue, rather than the "why"?

Life is Strange is for teens. BTW

I too think you need to explain more what you need to see in a game to consider it to target young adults, because I definitely thought a majority of games already had their main target demographic in the age span 14-21.

Rated T for Teens does not necessairly mean the game is targeting older adults.

But young adults are targeted, and tends to be the most popular crowd to appeal to. It's just that most games are exactly what you say, carbon copies of violence

I too think you need to explain more what you need to see in a game to consider it to target young adults, because I definitely thought a majority of games already had their main target demographic in the age span 14-21.

I suppose this depends on which country you are in and what rating system you use. I just checked game.co.uk top 20 chart for Xbone and it has the following Pegi ratings.

9 games with an 18 rating,

5 with a 16 rating,

3 with a 12 rating and
2 with a 7 rating
1 with a 3 rating

The PS3 and PC charts are very similar. The Wii U top 20 chart has no 16 or 18 rated games.


EDIT:
So I misread what the OP is getting at. And was assuming by young adults he meant teens but, now after re-reading it would seem that no he actually meant he isn't talking about games being restricted by age but by content that would interest the young adult age group.
On this I think he is way off the mark as nearly all games across all formats are aimed strongly at the young adult market. If you take a game like GTA, yes its violent and full of strong language but it is very tongue in cheek and squarely aimed at people in there early 20s. Skyrim, Fallout, Assassins Creed and Farcry are definetly aimed at the twenty hunger games, maze runner age group.

I was under the impression that about half the AAA out there were for young adults (if not more!)...

As an adult, I struggle to find products tailored to my need, and oftentimes find myself faced with artificially regressed products with characters that clearly depict younger protagonists than I wish it would. I was very happy to see The Witcher III succeed because I felt it was the first protagonist over 30 to actually make sense in a long time!

I think we have a radically different definition of what a young adult game actually is, and here might lie the issue, rather than the "why"?

Jap, I agree 100%...

So many stuff in the gaming scene is tailored to allow 12 years to also play the games (I can live with reduced gore, but ghost drivers in most wargames vehicles are pretty weird)... so much stuff is designed to actually attract the young adults market (as Orymus laid out, I also find it rather disturbing if EVERY hero is between 15 and 20 years old... which most probably happens to be the exact target group of most games.

Then there are the games with the steroid pumped Dudebros, or the faceless generic soldier. Just as with the the brainless generic stories of these games, if this appeals to someone, then it is to adolescent boys. They still think more is better (need moar steroids!), and they haven't read/seen enough generic stories to crave something different yet.

Then there are the stories and characters which are so retarded it makes me switch off the game immidiatly and never come back. I am no fan of blizzard games, they are just grinded down to spheres instead of having edges and imperfections that make something charming... they are way to mainstream for my liking.

I gave Star Craft II a try, and I quickly came to hate Blizzards way to appeal to Korean Full-Automatic-Mouse-Clickers with their stupid skill activations... but what really, REALLY made me kick the game into the recycle bin was the story of the single player campaign. I haven't seen/read such a crap in a long while (my helpless tries in finding an anime series that doesn't suck in the pile of crap online when I finished one I liked set aside)... this story was so clearly just ticking boxes, and every box was clearly tailored to adolescents.

Wild west saloon and revolver belts - Check.

Armoured badasses on steroids - Check.

Eyepatched badasses - Check.

Italo western "you cannot trust anyone" sh*t - Check

One Ship against the full might of an empire - Check

I am a mid thirties guy that still likes having some adolescent silliness from time to time. But I also like something more mature from time to time, and I am not talking about the kinky stuff here. I find it disturbingly hard to find any AAA game that actually NOT targets the young adult / teenage age group. Or at least targets them above everything else.

It's even worse in the Manga/Anime world, but lets not get into that... if there wouldn't be the odd pearl buried among the crap I would most probably stop bothering.

Yeah, JRPGs in particular, I think part of my growing tired of them was due to the fact that they all tended to center around very young, immature protagonists.