Let me tell you about elements of games I'm thinking about:
A girl is bullied at school to the point of committing suicide. This isn't a game of vindication. Justice isn't served. Things aren't set right. It's just how things are.
Your brother committed suicide a year ago. As part of the game you have to deal with someone who blames you for it.
A couple has to deal with the grief of their baby drowning in the bathtub. It's not an abstract thing. You as the player have to ensure the baby drowns and set the conditions for it to happen, knowing full well this will be the outcome.
You're a scientist stuck in a weird dimension and trying to figure out how you got here. Well, you got here because you murdered your wife and kid and then killed yourself but before you did that you made a copy of yourself and your family in a virtual world. That plan didn't work out well.
Edit: Just in case anyone gets deceived, the games aren't about these things but they do explore them as part of the game. The point is a lot of modern mature games tackle very adult topics.
Reading these descriptions, I have only one comment:
What the *HELL*?!!?!!!
Games are a medium to tell stories. If you can conceive a TV show or movie tackling these themes there's no reason to think games should be exempt. In fact they are far superior in addressing these themes than movies are.
Two of the games are made by former Telltale employees.
One of them is What Remains of Edith Finch (not much of a spoiler - plenty of other great stuff in the game).
Here's another good one: "Are there any health studies about what exposure to violence or horror does to childhood development?"
There is a reason that rating systems exist and that we shelter children from these things.
The pre-rebuttal that you posted "this was common in my childhood" is no indicator that this was a healthy behavior for you or the masses.
Ratings are very criticized by artists, eg as being fueled by conservative moms. For example, in the USA, movies with guns and explosion can be shown to younger audiences than nudity - seems very illogical.
Also, some anecdotes: lots of my friends were into GTA as kids, ie early teens, and turned out fine. Comparing to kids who didn't do so well, I consider the most important factors to br family, education, and finances, not violent multimedia.
With that being said, I'm sympathetic to limiting internet access due to communication with strangers, and extreme content (eg violent rethorics that appeal to action, not fantasy violence).
In reality I was 15 when they came out. The graphics in GTA weren't much different to Frogger. Doom and Quake involved blasting monsters, not people. Duke Nukem 3D, Halflife had very unrealistic looking people.
Todays games are very different in terms of visual quality, but even then, GTA is relatively mild compared to many games. You can hit a prostitute with a bat and kill her, but you can't drag a random person off the street and plunge their arm into a deep fat fryer.
But I will say the rating systems have not caught up to the reality of where the dangers of modern media are. I worry a LOT more about skinner-box mechanics, design choices that cultivate addictive personality traits, and communication systems that create openings for cyberbullying and grooming/sexual interactions with minors are much bigger problems that I feel the industry does basically nothing to even inform me about, let alone empower me to be able to manage it.
That was it. My entire argument was (and I emphasize WAS) that I didn't like no gubment tell me what to do. If I wanted to be a damn fool and kill myself why would they care? It's a stupid act to try to outlaw stupidity.
Then I found out that seatbelt laws are actually about decreasing the financial burden of underinsured accident victims. The "gubment" doesn't care if you die, but they do care if they have to fund weeks of medical support before you die despite the treatment, or if you survive but are disabled and wind up on social security.
That realization made me give up.
It was always about saving money, not lives. With seatbelts and airbags you are more likely to either walk away uninjured or at least not so injured that you spend more than a few hours in the hospital.