Out of all the video games I've ever seen, this is the most deserving of the rating "M." The language is an issue, and the violence and action will literally make you want to kill everything that moves at any loud, sudden noise after a few hours of play. I play this game on the computer with my son (going on 13.) We both have experienced the thought I just mentioned, and believe me, it isn't good. My son and I learned to limit our play time, and then it became one of our favorite after school games. He likes to look up the way the "necromorphs" act, what kind of people are used to create them. (sick people make "pukers" pregnant people make "pregnants" and your average Joe becomes a "slasher" just to name a few.) He looks up strategies to kill them, and grasps the whole "strategic dismemberment" concept. I am a little worried about how easily he tears the zombies apart, but he's not experiencing any symptoms of prolonged play that I haven't felt myself, and i find the necromorphs very interesting. Swearing is a huge problem, but ask yourself, if you were alone on a space ship where the entire crew has become zombies, would you swear a lot as well? My son hasn't used any language in front of me, so I'm not too worried.
Aside from the violence and swearing, the game is very emotional. My son and I get tense while walking through a dark hallway, scream when something jumps out, get mad as we get betrayed, use problem solving skills and intuitive thinking to get past malfunctioning machinery, and get teary eyed alongside isaac as he awaits his death. We've fallen in love with main characters isaac clarke and Ellie langsford, who display good teamwork and heroism. The bottom line is this game is fine if you limit your playtime.