Left 4 Dead 3 Accidentally Confirmed by a Valve Tour.
A person touring the offices as part of The International 3 tournament took a photo of a screen showing a changelog.
Which is showing you Left 4 Dead 3 and Source 2 as current projects.
If this is for real i don’t know but i sure hope so L4D was awesome. Do you want another Left 4 Dead ?
I only not hope Left 4 Dead 3 is coming but also Half Life 3 and Portal 3 would be nice.