Context In the animé Attack on Titan, armed forces use a special device called 3D maneuver gear (also called vertical movement gear) to move through the air. The system is based on a pair of grapp...

2021年4月12日 · Maybe an ore that produces that much pressurized air for something akin do the 3DMG, or whatever. Or some relic that can power clockwork robots. This could have a similar effect to magic stagnating tech, in fact, because it would impede "normal" tech progress.