Sorry if there's already a thread with this title...
I was thinking (after researching the alien corpses) that more techs need to have results other than just leading to another tech.
During my hunt for civ 4 mods I found a discussion on how best to construct a tech tree, in that discussion it was identified that no tech should be only a stepping stone for another tech....otherwise why have it?
With that in mind perhaps Zenonauts could inject in that every single tech gives a result beyond merely allowing you to research another tech.
The first tech "Alien invasion"? (the one that leads to the MIG plane tech) could perhaps give access to a unique story mission "cave investigation" perhaps in which your chinook is sent out to examine some cave drawings which reveal that the aliens have visited earth before, completing this mission unlocks a new tech "why are they here? pt1" which looks into why they've returned (going off at a tangent...)
The tech for the research of the plasma pistol perhaps allows you to sell the pistols for a higher amount....or perhaps just allows you to sell them.
The alien alloys allows you to produce minor plane hull improvements and a heavier armour (not as good as the final result of the path because it slows down your soldier quite a lot, so of dubious value)
Anyway the idea is that no tech only unlocks another research subject, it will also have some other benefit, be it a building, vehicle, object, passive bonus, or a hidden one-off mission (investigation type mission perhaps?...although either some kind of combat element needs to be added, or it's just a case of flying out with the chinook and back again)