Instead, I finish researching long bows level 5 (my choice), and suddenly have an option for 25% range increase on long bows that is totally random. It doesn't sub the range increase in for what I already got. It just gives me an extra little side tech out of the blue that I could chose to research.
Well, considering that it's the bonus that you actually
want, it actually makes no difference whether the randomness is in the appearance of the
tech or the
bonus.
Secondly, I'm researching short bows. Once I complete short bows level 3, I see a new tech line to an unknown tech that appears which is tied to something in the materials research tree. Once I've researched bronze, crossbows fill in the "unknown tech". For you, cross bows might be tied to long bows and bone carving.
The problem is, after one game, that tech line is no longer hidden. You know what to expect.
I should be able to research something that will be the counter to any unit in the game as a given, along a predictable research tree.
That would take some doing, as units will be player-designed and will vary drastically in stats and weaknesses, but it would still be possible. I like that, and think it will be in the game.
Nifty special extras like cheaper materials, increased range, etc. could be side techs that everyone will get somewhere, but everyone will get tied to different random units or other techs. You might get 25% faster rate of fire for bowmen
Since cost would (hopefully) be balanced, what you really mean is not random research but
auto-generating tech trees. THAT would be fun.