@Update: The Maintenance has finished and servers are back online. Check the Patch Notes here:
http://steamcommunity.com/games/331360/announcements/detail/486795433022793564
This Monday [17/04/2017] at 5:00am EDT [11:00 CEST] we'll be doing a full maintenance on all our services, which means that everything - Game, websites, forums - may be offline for the entirety of the maintenance. We expect everything will be back online by 1pm EDT [19:00 CEST].
We will be deploying a new update to Heavy Metal Machines during that time that will greatly improve game performance.