"Left 4 Dead 3" is in production and there is no official release date, anyone who tells you otherwise is just speculating on rumors.

Counter-Strike co-creator Minh Le has stirred fans' anticipation by assuring them that the game is under development and progress is moving along well. Le is no longer working with Valve, but mentioned in an interview with goRGNtv, "It wouldn't be any news if I said yes, I saw it. It looks great."

"So I was really excited when I saw that. I was like 'Wow, this looks great.' I really enjoyed Left 4 Dead. It was just one of those games that really changed the industry because I think at the time there weren't many good co-op games, so it was like, 'Yeah, this is a great co-op game'," he adds.

The first "Left 4 Dead" game was developed by Turtle Rock Studios, which has split from Valve since the 2009 release, and is working on the game Evolve for the Playstation 4, Xbox One, and PC. The second installment was released by Valve, but Valve has not said anything official about the matter.

There have been leaked screenshots of the game that have been re-made using Valve's new Source 2.0 game engine. The screenshots have come from a confidential slide show and shows a rebuilt Plantation level from the "Left 4 Dead 2" title.

The screenshots are only for a prototype and will likely change before the actual release of the game. They are however strong evidence that development is underway, meaning the most accurate speculation as to a release date puts it sometime inside the next year and a half.

The release date for "Left 4 Dead 3" may also depend on the release date for Source Engine 2.

Source Engine 2 will have next-gen graphics, better features and more interactivity.

To summarize, Turtle Rock Studios has split from Valve and is focusing on Evolve. "Left 4 Dead 3" requires Source Engine 2, which is not out yet. However, there have been leaked screenshots that seem to indicate Valve is working on the game, or that Turtle Rock made some progress on it before deciding to focus on Evolve. 

If it is in the works the release date probably won't be anything inside of a year. Check back for more information as it becomes available.