Valve is one of the most secretive developers in the gaming industry, and that drives fans into an absolute frenzy any time there's even a hint of speculation about the company's plans. Though the wait for Half-Life 3 will likely take us into the next millennium, we might not have to wait that long for another sequel to Left 4 Dead.

According to CVG, a group of DOTA 2 players was given a tour of Valve's offices this past week. While there, an observant tour member snapped a picture of a monitor displaying the company's internal changelog. Normally, this wouldn't be a big deal, however the changelog screen happened to be displaying a record of "L4D3" and Source 2 at that very moment.

The code "L4D3" isn't terribly hard to crack (Left 4 Dead 3), but it is a little curious that the code line just happened to be there at the time the person took the photo. Valve has already stated its been working on the Source 2 engine for some time, though hasn't mentioned just when it will be put to use. Perhaps Left 4 Dead 3 will be the first Source 2 game. Perhaps this is all an elaborate ruse. Perhaps Valve set this whole thing up on purpose.

Whatever the case, there's a strong pile of evidence building supporting the announcement of one or both of these Valve items. Now it's just a matter of (Valve) time until we learn the truth.