This should be a given. The Last of Us is a mature, dark story about survival in a harsh, post-apocalyptic American landscape, and it's sure not pretty. However, movie executives, being well aware that most violent video games are played by a lot of teenagers, try to sneak as many video game movies as possible through with a PG-13 rating, the idea being that this will generate them more revenue, regardless of how badly it ends up butchering the source material. Just look at Paul W.S. Anderson's Mortal Kombat: it captures plenty of the imagery of the video games, but is totally hamstrung by its meek PG-13 rating, which means the movie cannot include surely the most iconic and important part of the video games: the gory fatalities. Simply, if The Last of Us is PG-13, be very afraid.