Valve’s collaboration with Overkill was not quite as exciting as some might have been hoping for. The Swedish developers of co-operative multiplayer PC and PlayStation 3 game PAYDAY: The Heist teased players with a Left 4 Dead-themed crossover between the two games throughout May. Even after the collaboration’s official announcement at E3 2012, it wasn’t clear exactly what the new PAYDAY level, titled “No Mercy,” was in relation to Left 4 Dead. Was it a prequel to Valve’s game, canonically linking the two series? What was Valve’s role in its creation?
Chet Faliszek of Valve clarified things according to Kotaku (via Eurogamer): Valve didn’t work on it and it is not canonical.
“This is a 100 percent Overkill made mission for PAYDAY: The Heist simply set in the No Mercy hospital from the Left 4 Dead series,” reads an email from Faliszek, “It’s not telling the origins of the infection and is not canon. There is a little cameo from one of the L4D characters (the comic should give you a hint) and a fun little Easter Egg with a payoff later in Left 4 Dead. Just us having some fun with a studio we are friends with and who have also made a great co-op game.”
To quote the many players who love Left 4 Dead: Aw, shucks.