True, but it will be quite a while before I can rejoin the fun, and if the amount of discussion that has happened in the few weeks I've been absent is any indication, by the time I'm back, Leo Tolstoys "War and Peace" will pale in comparison to what I've to dig through the get up to speed...Keep in mind that this tech tree rework is a massive design work that will take a lot of time before any real implementation, so you indeed have time to participate in the discussions.
Sorry, confused the two. As I said, I only skimmed very quickly and superficially over the discussion. But yes, my "Robotics" and "Large Scale Building" overlaps very much with your "Cybernetics" and "Mech" themes. Although I think there would be subtle differences and nuances, my themes would probably more "narrow" in that they really completely lack certain things (going along with my general idea of having more, but more restricted/narrow/limited themes, and no single theme strategy possible).Your Robotics is currently within Cybernetic (automation, AI, nanotech and other complex technologies).
Mech have the megastructures. It is more industrial than robotic in that sense. Even steampunk.
I'd see "Crystalline" related stuff as part/subset of the "Lithic" theme. "Lithic" would be more general, the entire asteroid hull line would fit in there. There could/would/should also be more asteroid related stuff: Asteroid Habitats (enabling colonizing asteroids), Advanced Asteroid Mining (of course other themes should also contain "Asteroid Mining" techs, but the Lithic theme should be best at asteroid mining), etc.Lithic can be the to-be-added Crystalline theme.
I'd definitely split Psionics off of Energy. Energy (or "Advanced Energy Manipulation" as I'd call the theme ) is where I'd put Lasers, Plasma weapons, (energy) shields (e.g. Deflectors and Plasma Shields, the current Blackshields on the other hand could belong to an entirely different theme), the Energy Hull line etc.Maybe I should consider a splitting Energy into two, Physics and Psionics.
Psionics is a very different thing. There I'd put e.g. special psionic "weapons" (psionic attacks on enemy ships), mind control techs, powerful special Influence, diplomatic, espionage and sabotage techs, research/learning techs, techs that help manipulate/control population (supression of revolts, keeping the people in line with the government, that sort of thing ).
While we certainly can and should incorporate some social/influence/diplomatic/trade related things into the themes you mention, I wouldn't pack all that into themes that are actually very technology related (technology in the more narrow sense of "Physics" and "Engineering"). I'd prefer to have some themes that are specifically focused on the social/etc. kind of techs. As lined out above, the Psionic theme could provide a lot of interesting ideas/possibilities in that area. Another idea could be "Advanced Psycho-Social Studies", dealing with things related e.g. to large scale psychological and social dynamics in large interstellar, multi-species societies (my inspiration for that is that "Psycho-Social" thing Asimov had in his Foundation triology - interesting SF-stuff, if you're into that kind of thing).I think I can come up with some quite differentiated social/influence/diplomatic/trade "techs" for different trunks. E.g. Mechanical can have the concentration camps, Energy could have some late game influence project regarding a very bright star (non-stop supernova) visible from any planet in the galaxy, Biotec and/or Cybertec could have techs related to hive-mind, communism and the such. Etc.