I always liked the idea of Cthulhutech. Turning the Cthulhu Mythos into an alien invasion scenario, and fight it out with Mythos beings with huge mecha? What's not to like?
However, as the setting was expanded I felt that it did not live up to the potential of the premise. Too many setting elements seemed implausible, and too often adventure and story potential were restricted rather than enhanced. In my view, one of the most problematic examples of this was Chapter Two of Mortal Remains, which details the New Earth government and its people and territories. Therefore I will be going through this chapter section by section and analyze what I would do differently. For this, I have the following design guidelines:
"One cannot, except in immature pulp charlatan–fiction, present an account of impossible, improbable, or inconceivable phenomena as a commonplace narrative of objective acts and conventional emotions. Inconceivable events and conditions have a special handicap to overcome, and this can be accomplished only through the maintenance of a careful realism in every phase of the story except that touching on the one given marvel."
Cthulhutech obviously has quite a few "marvels" - that is, "out-of-the-ordinary" setting elements which can break suspension of disbelief. There is the Cthulhu Mythos itself, the mechas, the occult and the psychics, the Aeon War itself... These form the core of the setting and must remain. Yet to make horror possible, anything outside of these core concepts should be presented as plausible as possible. If the heroes are to be defenders of a society on the brink of extinction, they have to feel, at least during the game, that this society exists and is worth defending - which is difficult if various setting elements feel implausible.
2. Making full use of Earth
"That's why, for the longest time (and still), my fundamental setting design policy was: "Use Earth." It's better mapped, better documented, and just plain weirder than anywhere else."
Earth, with all its history and diversity of geography and cultures, is an amazing world - truly "the most detailed game setting there is". And one of the main reasons for using Earth as the base for a published setting is that game masters can tap into all this diversity to come up with new story and adventure idea. Any setting description should therefore pay homage to this diversity - it doesn't neet to provide exhaustive detail, but it should inspire ideas and give the game masters ample motivation to research the region and expand on it beyond what the "official" materials cover. This diversity should not be removed without good reason.
There are quite a few people who want to rewrite the setting from the ground up. I am not so ambitious - I want to make any changes fairly self-contained. The fundamentals of the setting should remain as they are, changing in presentation rather than substance, and more radical changes will only be on a lower, "local" level in order to avoid invalidating other material for the game.