Development progress for Valve's upcoming next-gen Source 2 engine and the previously leaked Left 4 Dead 3 has recently been found on an internal changelog system on a monitor within Valve HQ. As many of you will be aware, Valve are currently busy hosting the the multi-million dollar International 3 Dota 2 tournament in Seattle. As part of the event, a variety of fans, including members of the Dota 2 subreddit board, were recently given the opportunity to visit Valve HQ for guided tours, with one such tour being documented by the founder of the subreddit, ReaverXai, who has uploaded a variety of photographs from the Dota 2 workstations. While the majority of the photographs provide previews of upcoming merchandise, the development team's preparation for the International 3 tournament, and miscellaneous shots of Valve offices, one particular photograph appears to show a changelog system on one of Valve's monitors, a list which includes multiple internal updates for Dota 2, Steam, Valve's websites, Source 2 and more. Each update features accompanying icons to help identify which product the change is related to, as shown in the image below. Click the image above for a closer look at the original changelog list, or check out this extremely high resolution version for an even better look. The full list, shown above, includes multiple references to Source 2 and the upcoming Left 4 Dead 3, both of which have had their existences leaked multiple times in the past. The original full image features a total of 11 changes for Source 2, some of which we have included in text format below. For those wondering about Valve's other projects - the list also includes 15 references for Dota 2, 4 for Steam, and over 17 for Valve's websites. Every change on the list is an internal update made to Valve products in a 2-3 hour period yesterday afternoon between the hours of 1pm and 4pm. These changes, while not necessarily important, show that Source 2 and Left 4 Dead 3 are both currently deep in active development, with Left 4 Dead 3 most likely still in the early alpha stages of production, as shown by the reference to a simplistic "devtest level". While the list appears to feature no direct references to Half-Life 3 or any other potential Source 2 titles, we should stress this is by no means a true representation of all the internal work going on within Valve at this time. It may still be sometime before Source 2 and/or Left 4 Dead 3 are revealed and released to the public, but I'm sure we can all rest easy knowing that both projects are still getting the attention they deserve from Valve's developers. We'll be sure to bring you any updates regarding Source 2 or Left 4 Dead 3 if and when we learn more. We also recommend you check out the original photo gallery, available here, if you're looking for some behind the scenes information about Dota 2, the tournament or some upcoming merchandise.