Come, witness the ways a writer gets to creating.
I love giant robots. That means I love my mecha anime, and while I got into Super Robot Wars V I began digging into the series mashed up in that game. The Mazinger series got my attention due to their blending of Ancient Aliens with Super Robot tropes, and the excellent blend of that series with Getter Robo got my attention.
I've run around Crazytown for years now. Ancient Aliens, Art Bell, David Icke, etc. are my jam. So, when some of my pals got into Attack on Titan, I--spoiler junky that I am--hit up the wiki and read deep into the lore. That manga, and I presume the anime in time, will reveal the severe conspiratorial element holding up the plot.
So I got to thinking, especially after seeing how well the Titans of the aforementioned comic and series correspond to the Nephilim of Christian mythology and its pagan counterparts worldwide. (Man-eating giants are common mythological elements.) We already had the Godzilla films and Pacific Rim do Giant Robots vs. Giants, and there's plenty of stories about smaller robots and powered armor versus monsters, but if it's well-known it's either old or Japanese (with a few exceptions).
So I got out the metaphorical blender and threw my ingredients together.
I'm still adjusting the results to suit; I want a thrilling and entertaining story first and foremost, so adjustments for that sake are ongoing, but I have a clear plan following a proven pattern. Initially you're looking as something that wouldn't be out of line for an X Files episode, and if I can get favorable comparisons to Bio-Booster Armor Guyver then I know I'm hitting the mark. Each escalation is a defacto genre shift, eventually going full Super Robot.
And no, none of this blackpill despair porn. (Looking at you, Evangelion.) I know my sources, and I know how those end. There will be a future for the loyal, for the faithful, for those that never give up and never give in, but you've got to grit those teeth to get it.