Poor Valve. You let some people in to have a look at the new merchandise and preparation for The International 3, and they walk away with a photo of some dev material.

More exactly, the visitors snapped a screen of changelogs, which include references to both the Source 2 engine and Left 4 Dead 3...

No Surprises - Left For Dead 3 And Source 2 Spotted At Valve HQ

The pictures were actually taken from the devs PC, which lends a little more weight to them, but it's not actually that surprising; Valve have said they are working on the Source 2 engine in the past, and with the Left 4 Dead formula being so simple, it's no wonder they're making it. If you can't read the image on the right, the infamous Cyborgmatt got us a zoomed version:

Of course, the question is if Valve are also working on another game with a 3 in the name, which has always been pegged as coming out on the Source 2 engine.

Ignoring that, there's some great photos of the merchandise on sale in the album here, as well as a general look around Valve HQ.

With only a few more heroes to add into DOTA 2 from the original, and the community created items working as well for DOTA as they are for TF2, it may not be long before much of Valve moves off onto their new projects, if they haven't already.

It's worth remembering that the Steambox we were promised this summer still hasn't arrived to face off against the next gen offerings from Microsoft and Sony. If Valve were to have a strong, controller capable title to release with the box however, it would definitely help sales and solidify the console's release.

What do you guys think, will we see Source 2, Left 4 Dead 3 and the Steambox all at once? Will it be out for this winter, or are we still years away? Tell us below!