Game developer Valve remains tight-lipped about any details on the third installment of its zombie-themed role-playing game "Left 4 Dead." However, there are already numerous rumors about the game's third offering.

Valve is rumored to be developing "Left 4 Dead 3." This speculation came after a leak came out that shows an employee of the game developer's folder labeled with "left4dead3." According to reports, the employee who shared the screencap is Tristan Reidford. It was just supposed to be a guide on importing source engine assets to Destinations platform for "Left 4 Dead 2," but the screencap included the "left4dead3" folder.

Other reports also speculate that four new playable characters may be added in the third installment. The rumored characters may include 24-year-old Katherine, comic book nerd Keenan, famous Kenpo fighter Garret Jr., and gangster member Irvin.

"Left 4 Dead 3's" story may also be considered a prequel and sequel to "Left 4 Dead 2." Apparently, it is set when the infection has started to spread. The mission campaigns that are rumored to be included are Inquisitor Land, Cliff Hanger, Early Destination, No Mercy, Crashland, No Mercy, and Impasse. Aside from these campaigns, there may also be a revamped backpack system that enables players to carry a single item at a time.

Even though numerous rumors have positively indicated that "Left 4 Dead 3" is indeed in the works, some reports are also speculating that the game franchise may end up like Valve's other hit game, the science fiction first-person shooter "Half Life 2." When the sci-fi game came out with its second installment in 2004, there was no single full sequel release after that.

As for "Left 4 Dead," the last full sequel came out in 2009. Since then, the last downloadable content it released was "Cold Stream" in 2012.

Fans are hoping that a word from Valve about "Left 4 Dead 3" should be announced soon, perhaps, next year.