Great game but inappropriate for young children
This is a wonderful game, with the best and most realistic scenery I've ever seen. It is completely immersive and includes an unlimited amount of tasks from doing chores to help the camp to hunting and fishing across the giant map. It takes 15 minutes of real time to ride a horse from one end of the map to the other.
However, the main character encounters, and sometimes causes, extreme violence against all sorts of folk. At one point he helps kill half a town, including all the lawmen, just to break his insane colleague out of jail. He slightly admonishes his colleague for murdering two extra people just to retrieve his guns, but that's the extent of it.
At another point, while simply roaming around, I encountered a person who had been strung up under a bridge, decapitated and missing the lower half of their body. Inside the head's mouth was a note from the murderer.
For people worried about sex or nudity, there is very little. And the gratuitous and graphic violence is potentially much more harmful for young children than any of the minor sexual themes. Also, the language is as bad as it gets, but again, is nothing compared to the gore.
I put 16+ because I think most 16 year olds would be able to handle this game without any more damage than an adult might endure. But each parent should evaluate their own child's tolerance for violence that could be traumatic or desensitizing.
Again, this is a great game, but know what you are getting. Almost every "shoot 'em up" game on the market is less violent. Except GTA5 of course.