https://www.pcgamer.com/dying-lights-free-content-drop-4-is-a-new-prison-heist-mode/

Dying Light continues its 10in12 loyalty bonus initiative with Content Drop #4 and Content Drop #5. So far, the free-stuff-for-playing run has given us weapons, attachments and community events. Number four, on the other hand, brings with it a new mode named Prison Heist. 

Designed for seasoned zombie killers, players are set loose on Prison Island—"the most isolated part of Harran"—and are tasked with breaking into an armoury against the clock. In either solo or with pals in co-op, the faster you get the job done the better the reward.