The ESRB has given Metal Gear Solid 5: Ground Zeroes a "Mature" rating. The ratings board's description of the game demonstrates that the game earned its "M" with a combination of violence and sexual content.
In Ground Zeroes, Big Boss must infiltrate Camp Omega, a secret American base in Cuba. The U.S. government has two important prisoners detained here: Paz, a Cipher agent that Boss defeated in Peace Walker, and former child soldier Chico Libre. Boss hopes to rescue both.
Big Boss' search for Paz and Chico won't be a bloodless affair. The ESRB mentions that he'll be killing enemies with firearms and explosives. His stealth executions include choking and knife-stabbing. Boss can even kill civilians or other prisoners. The ESRB notes that there's slow-motion during battles so you'll get a long look at the blood splatter.
The ratings board also describes a grisly moment in the game where we get to see a character's digestive tract.
"One cutscene includes a depiction of blood and gore (e.g., a character's intestines exposed during a dramatic procedure to remove an object)."
They're talking about a surgery scene from the Ground Zeroes E3 trailer. Boss and his companions are removing an object (a bomb?) from the abdomen of a woman with cropped blonde hair. The woman appears to be Paz. This scene begins about two minutes into the trailer:
Players will also overhear a sexual assault of a female by several male assailants. There are no visuals but players will hear the characters struggling and the woman's clothing being ripped. They don't mention who the victim is but presumably it's Paz. Not a fun game for her.
Ground Zeroes is a prologue to the story of MGS5: A Phantom Pain. The game also serves as a showcase to the abundant gameplay changes that the new FOX Engine brings. Ground Zeroes and Phantom Pain are more open-ended than previous entries in the series. Players can freely navigate the game world on foot or with vehicles like planes or motorcycles. They can also decide what order they'll complete missions.
Konami will release Ground Zeroes in Spring 2014 on Xbox One, PS4, Xbox 360 and PS3. PS4 and PS3 gamers will get an exclusive "Classic Snake" mission Xbox 360 and Xbox One owners can look forward to a mission starring Raiden.