You seem to be looking for Conspiracy books. Would you like some help?
Sumerian gods used to be the slavers of humanity, but that happened in a parallel history a long time ago. Now, that history was/is undone, but not permanently, at least not necessarily. Today, the remnants of that history occasionally emerge, trying to set wrong that once somehow turned right. And our secret organisations are waging a war in the shadows to prevent that.
There's spooky mind-magic, monsters that seem to be influenced by both Robert E. Howard and Howard Phillips Lovecraft, and eerie tech. Also psychological horror. I think this is the closest match to what you seem to be describing.
Various Alphabet Soups and their agents are fighting against alien and supernatural menaces, unified into Aegis. A lot of focus on pulling strings and operating at the organisation level.
Sign up into the Company - an élite supersecret organisation consisting of the best of the best. Off the books, with a great budget and the fanciest of toys. Become the world's most hypercompetent commandos, technicians and so on. Fight aliens, gargoyles, warlock cabals and more.
A game of magical conspiracy. Various supernatural creatures participating in a mutual-assistance society hiding from the muggles.
Keep in mind that most of the books are aimed at Third Edition (except the new Madness Dossier), which is commonly considered to be less elegant and less balanced in certain areas (notably psionics); some conversion may be required.