Just Cause 3 Multiplayer mod is a free fan-created project bringing an explosive and highly-customizable multiplayer to the critically acclaimed action sandbox game. Get ready for countless hours of hilarious brawls, stunts and races with hundreds of other players!
For a more detailed list of the current options and instructions on how to install and play the mod, please see our FAQ on the Steam discussion board here:
http://steamcommunity.com/app/619910/discussions/0/1457328927827817919/

We at Nanos are an enthusiastic team of coders from Germany, Austria and the UK who have worked towards releasing Just Cause 3 Multiplayer for more than a year. Our goal is to bring multiplayer to the next level by allowing the players themselves to build upon our work!
KEY FEATURES:
Battle, race, chase and play tag with fighter jets with up to hundreds of players per server.
Enjoy community created gamemodes, ensuring a constantly evolving play set.
Countless hours of fun including racing, deathmatch, skydiving, freeroam, etc.
Don’t see the game mode you want? Make one!
State-of-the-art synchronisation helps reduce lag to a minimum.