It is a game called Player Unknowns Battle Grounds. It is a game that has taken the concept of Battle Royale (or H1Z1: King of the Kill, or The Hunger Games) . A number of people are released onto an island and basically last man standing wins. A simple concept where you have to find weapons and kill people.
Every game has about 100 people fighting against each other so it is a serious game and there is danger at every turn. There seems to be two different tactics being played out. Go and kill as many as you can in mad dashes or hide away until there are less players to fight.
Hiding seems to be the smartest tactic at the moment but is still tricky trying to get to the safe zone. The game hasn't been released yet but is expected within the next month. There is a test version which everyone is currently using but is expected to be a big hit when it finally arrives.