A flywheel is an in-game device that provides you with energy as you move. The more you walk, the more energy you have.
Given to every player right after registration. Spins up from walking and turns; at maximum speed 10 it gives 5 units of energy every 5 minutes. It slows down on its own over time if you stand still.
A bonus flywheel — bought in the shop or awarded for achievements. It has a reinforced "winding", so it slows down more slowly and runs at a maximum speed of 20: it gives 5 units of energy every 24 seconds.
The flywheel picks up speed on its own while you move across hexes. A few simple rules help keep it "charged":
Energy accumulates in the flywheel first, and is then credited to the player. You see a blue bar moving around the spinning flywheel — when the bar closes, the energy is credited.
The energy accumulated by the flywheel goes toward opening new hexes, building structures, and destroying objects on the map.