Headquarters Lv31
- Research Center Lv30
- Tank, Air or Missile Center Lv30
- Barracks Lv30
- HQ Expansion Lv1 (last research of The Age of Oil tree)
HQ 31-35 Reqs
Requirements for Headquarters upgrades from level 31 through level 35.
Upgrade Requirements
Headquarters Lv32
- Research Center Lv31
- Tank, Air or Missile Center Lv31
- Barracks Lv31
- Wall Lv31
Headquarters Lv33
- Research Center Lv32
- Tank, Air or Missile Center Lv32
- Barracks Lv32
- Hospital Lv32
- Drillground Lv32
Headquarters Lv34
- Research Center Lv33
- Tank, Air or Missile Center Lv33
- Barracks Lv33
- Wall Lv33
- Alliance Center Lv33
Headquarters Lv35
- Research Center Lv34
- Tank, Air or Missile Center Lv34
- Barracks Lv34
- Hospital Lv34
- Drillground Lv34
Reference Screenshot
