That came in, in a much bigger way with Alpha 16.
My Alpha 11 is, I think, VERY heavily modified to extend the game play and make exploration both much more necessary and easier to, but it's all XML edits (apart from a couple of AsssemblyCSharp.DLL edits), because mostly that's all we could do back then.
I'd be perfectly happy to share it if anyone asked for it, the basic mods being to extend exploration, ore use, armor and tool tiers, a completely reworked RWGMixer along with other stuff like insanely dangerous cities. I could be more detailed about if anyone wanted to try it out.