I really like the Technology, but I would like it to get scoped out a little better. It seems like finding out what techs lead to is totally "random" and found out via trial-and-error more than anything (if I keep going down the Civ line, I eventually get Houses) rather than knowing exactly how many more levels I need before I can get X techonology.
I DO like your techonlogy system, and I DO like how it is random. But it would be a little nicer if there were a few resources available that helped explain some core technologies and what I need to get them.
Also, what happens if you do a research on something with 2 "uncommon" technologies and you fail to discover both of them? did you just waste your research or are you guaranteed to always get a technology every level?
Finally, even though I like how you can leave a technology un-researched for a very long time and it isn't crucial, it is sorta weird having to spend 20 turns discovering Bee Keeping when you have Unicorn Ranches, when Bee Keeping was available early on, and Unicorn Ranches just very recently. Could we have "free techs" where if you have a particular common research in your research queue for more than 5 levels (or something like that) you get it for free? I know this means that prioritizing uncommon/rare techs is better than "ever" picking up a common, but you could make it like 7 or 8 levels which would work out to nearly 100 turns or so. 100 turns is a long time to go without some basic technology...
Or maybe these old technologies get less-and-less valuable so you can pick up 2-3 "old commons" at once with one breakthrough, which helps balance spending a long time getting an old technology you could have gotten a long time ago and then getting it for free because you procrastinated long enough.
The third possibility is diplomacy, espieically espionage. I'm against trading Technology, but perhaps old-old technologies become available for trade after a certain period of time. Or they are super-easy to steal, requiring just a small investment to spies.