

Keep the civilians down and get me into the hospital patient database. In the Payday: No Mercy trailer, players are instructed "We need to draw some blood from a guy that they have in quarantine. "Have you ever wondered how the Left 4 Dead series began? It started with a heist!" read the description on a trailer posted to YouTube (which has since been pulled from its official channel). Interestingly, the collaboration between Valve and Payday developer Overkill is more than just an authorized use of a Left 4 Dead map, however, as the "No Mercy" mission delves into the lore surrounding the zombie infection.

In Payday's take on Mercy Hospital, players will face waves of heavily armed cops and SWAT officers, not zombies, in an attempt to recover a blood sample. The mission-based game sends up to four players on heists that typically involve grabbing cash or goods while managing hostages. Payday: The Heist is the cooperative multiplayer shooter developed by Sweden-based Overkill Software and published by Sony Online Entertainment. Valve has lent one of Left 4 Dead's most iconic campaign maps, the climactic "No Mercy" hospital level, to Overkill Software's Payday: The Heist for a most curious crossover. Left 4 Dead meets Payday: The Heist in new crossover campaign.
