Metal Gear online will be going live on the 6th of October 2015, and if you already own MGSV you automatically qualify to download it for free.
What makes Metal Gear Online unique is that it is one of the few online multiplayer games that rewards you for being sneaky as well as not killing your opponents. The game has several classes: The Scout who is a long range specialist (sniper class), the Enforcer who likes to go in guns blazing and the Infiltrator who is your close combat expert. Each of these suit different playstyles and have their own unique qualities that they bring to the team.
Below is a gameplay demo of these classes in action: