We could go researching tech and stages.
Okay, Humans are stage one, and they're faced with a dilemma. They want to research stage two, but first they need to research two stage one technologies. They have the choice between the chaingun, shotgun, lasgun, and battery pack. Once they've researched two of those, they can start researching stage two. At stage two, since there's more things to research (defcomp, flamer, helmet, grenade, pulse rifle) they have to research three things. At stage three, everything becomes available.