Metal Gear Solid V The Phantom Pain isn't due out until September 1st but the game is complete enough to have been submitted to PEGI for a rating.
Pan European Game Information is a content rating system which assigned an recommended age to video games for the information of parents and consumers. It's a voluntary system but has been adopted by several countries in the EU and is recognised as a way to determine whether a game is suitable, particularly for younger players.
The rating for Metal Gear Solid V The Phantom Pain is, unsprisingly, 18 making it suitable for adults only. The detailed breakdown of the ruling contains the following content:
"Extreme violence - Multiple, motiveless killing - Violence towards defenceless people - Strong language"
The highlighting of motiveless killing and violence towards defenceless people will surely gain the game some extra attention, and it's probably the kind of working which publisher Konami won't be all that happy about. That said, the Metal Gear series is hardly targeted at children or young teens, given the extreme nature of its content. Sons of Liberty did earn a 16s rating for its HD remaster back in 2011 so it's certainly going to be one of the more violent games in the series.
Metal Gear Solid V The Phantom Pain comes to consoles and PC from the 1st of September 2015.