The Industrial Age is the game’s first great rupture. The walls and castles you spent three ages perfecting are suddenly answerable from a distance, and a new resource — Oil — starts deciding who can field the new machines.
Economically, industry changes the tempo. Refined production buildings mean armies rebuild faster, which makes wars longer and economic depth more valuable. Empires that treated their economy as a means to a medieval army now need it to become an engine.
Strategically, this era rewards players who adapt early: artillery to crack fortifications, updated defenses to answer enemy guns, and a resource plan that secures Oil before your rivals lock it down. The empires that struggle here are usually the ones that won the Imperial Age and assumed the same playbook would keep working.