Survivors is a multiplayer content in Resident Evil 6 and is one of the 3 Multiplayer DLC that was released, alongside Predator and Onslaught.
Survivors functions similarly to its Resident Evil 5 counterpart, with the exception of being able to equip skills. There are 2 types of 'Survivors' modes:
Survivors: A free for all match.
Team Survivors: A team-based deathmatch.
In Survivors, players are pitted against each other similar to a deathmatch with limited time. Although characters have their own starting weapon, they can find weapons scattered throughout the stage.
Human characters who are killed become zombies or J'avo depending on the stage and must kill another human character to play as the human character again. The game ends when the last man is alive, or the timer has run out, with the player having the highest score winning the game.
It seems that before every round of Mercenaries, the same three special weapons spawn in the stage in one of three sets of locations. The weapons an Elephant Killer magnum with five rounds, Rocket Launcher with a single use, and a Grenade Launcher with six explosive rounds. No additional ammo for these weapons can be found. It also appears that these spawn locations are in one of three sets, where when one set is used the that special weapon will always be found in the same place. It seems that a round never uses the same set as the round before it. See below for a map of the weapon spawn locations for each of the three sets for the Urban Chaos map during Survivors mode.