[Kemal]

As for the tech tree, don't forget that mandatory tech requirements are noted in the upper right corner of the tech they are required for, via a little tech icon. You always need those techs in the upper right corner to research that tech, whereas the lines, iirc, indicate that the tech the line comes from "leads to" a "new tech" (you only need to possess one tech of those that have an arrow leading to the "new tech" to research that new tech, not *all* the techs that have arrows pointing to this "new tech").