the build tree is different from research, which is a little confusing.
hover over phase to see the requirements for the next phase.
as for activity, that may be hidden in some emails?
The problem with the research tree is that it only says
"??? Not discovered yet"
Without any hint of HOW to discover it.
If it is a RESEARCH tree, then I expect to be able to do Research to unlock the things, either by trying combinations of things, learning more deeper science about the things, or in the most boring cases spend points to unlock the research.
But these "unlocks" seems to be tied to the story that unfolds through the emails? or something like that?
So maybe it should instead be called "crafting logbook" or something like that?