The number of Force you have, is indicative of your overall power. The current Force is always displayed next to your General's avatar.
In order to increase it you can:
- Construct and upgrade Buildings and Add-ons
- Recruit more Troops. The higher their tier the more force you'll gain
- Complete Researches or craft high grade Equipment
If you wish to see a breakdown of your force, tap the button on the main command interface.