I feel like you reacted to part of what I wrote without reading the whole thing.

I'm also going to point out that I've been carded while buying a game rated M on more than one occasion.

So. Regardless of what the ratings mean, in practice, there's a lot of things that go into how people perceived them.

How does Steam or Valve market these games to children exactly? In order for me to buy Halflife 2 on disc I literally had to show ID.

My older brother had to buy the first game because I was too young. My parents knew about and did not care about the ratings. My father in particular played the games with us.

While these are the only two Valve titles I've played and they aren't online competitive games, I really would love to hear why you think the games are marketed to kids.