Revisions for Zombie State: Diplomacy of the Dead. This revises (a) the initial difficulty rules, (b) the tech tree, and (c) the player aids.
Fundamentally, this product introduces the idea of sliding difficulty, retools the tech tree to be more balanced / interesting, and creates new player aids that are vastly easier to understand.
Printed correctly, there should be two half-sheets for the tech tracker, two double-sided half-pages per player, and a few pages of new events. Use 8.5 x 11 pages, print horizontal, and cut as appropriate. All files ready to print on PDF, after much work at the print shop. Print on cardstock, or laminate, as desired.