A plan to skip most Castle Age military and reach the Imperial Age early, often called FI. It is mostly seen on closed maps such as Arena or in team games where the player is protected.
The Imperial Age costs 1,000 food and 800 gold and needs a Castle or two Castle Age buildings. The payoff is access to units and upgrades the opponent cannot match yet, such as Bombard Cannons, Trebuchets or a fully upgraded unique unit.