Better late than never!
Blacklight: Retribution on the PlayStation 4 just got a new update today, and with it came the Onslaught horde mode. This new mode sees four players working together to fight off endless waves of infected creatures. You know, typical horde mode stuff.
Today's update also includes two new multiplayer maps called Metro and Decay, the addition of private servers, matchmaking improvements, better frame rates, faster loading, and various other fixes to the overall game. And of course this is all available for free.