I put in a few builds on Valley 2, though they don't go back that far. And I put in some from AI War that go back to the first preview of 6.0.
The main problem is that in late 2012 Steam switched from an older data format to a new one, and the data format from the older "steam2" data format isn't available in the newer builds system. Basically it was a process that upgraded from being less flexible and more manual to being something devs could completely control, and things from before that just weren't as well organized in general.
There wasn't anything useful on Valley 1 in terms of older versions because that work was mostly in 2011. There are older builds for TLF and Bionic and so on, but the site started getting slow and I had some other things I needed to do, and you hadn't mentioned those as being of that much interest, so I didn't do them.
For AI War, there are indeed "demo" versions around the internet that are the full game, but require a license key to unlock. For our older games in general, that was how we did them so that we could give away the demo files publicly and also offload some of our bandwidth costs. That makes it so that if you go back into the older versions on steam it will ask for a license key you don't have, though, which kind of further compounds things. I don't remember when we first stopped using the license key system: maybe Shattered Haven and then onward?
