I think That Space Empire 4 had 1 nice concept

It had various research trees. 1 main with common tecnologies to all races. And other smaller trees for special tecnologies that you could buy with race points (before starting the game, like moo2). The tech trees were about "psychic powers", "organic manipulation" and so on.

I think thats a good way to go.

Each race could have 1 or more unique tech trees besides the main (common) tree, and you could custom your race using race points to get the extra tree. You could even put tech nodes that required techs from 2 or mor trees (like a psyonic machine, or an organic quantum-based computer. Imagination is the limit).

The bad side is that it was divided by areas to be researched in a sucessive way (like moo2) but in SE4 it had too much areas to coose (even in beggining) and a reseach could generate too much branchs. So it was a pain to choose what to research. The brilliant side was that you could research various techs at the same time.



In reality (as we can see in history) the civilization tend to create an unique culture while isolated, and evolve in a peculiar way. But with contact with other civilizations, they tend to trade tecnology (by trade or war) and in the end we get 2 very similar cultures. The weapons get similar, the tools, etc...

I think in a galactic race it should be similary true. Of course, humans cannot mutate his body to a ship, but when with contact with an all organic race using organic ships we will want to research ways to make organic ships. If well using or not (or well use some hybrid tecnology) will depends if our technology is superior enough to take out their organic ships. The same goes to the organic race. If they DO research, they GONNA research metal/silicon use.

The tech tree should achieve that. The races should start with diferent techs, and later in game (by trade, spy, war,...) become equal techs.

That means that humans could not start with psionics research tree, but then assimilated the tech, they could reseach further without help.

As for an open ended game, I think it is great, but it must be an ending objective (kill everyone or make an united federation). You could put an tech tree, and then it ends it goes for the numbers... "propulsor #13" for instance should give "engine #13" and "fuel #13". Well, it dont sounds fun, but its much better that dont having anything to research anymore.