The GDF research tree focuses on enhancing unit durability, firepower, and utility. Key research buildings include the Research Lab and the Advanced Vehicle Bay. Prioritize upgrades based on your current mission's challenges:
- Infantry Enhancements: 'Improved Ballistics' (Riflemen damage), 'Advanced Medkits' (Medic healing), 'Grenade Launcher Upgrade' (Grenadier utility).
- Vehicle Armor & Weapons: 'Composite Plating' (vehicle armor), 'High-Explosive Shells' (tank damage), 'Targeting Systems' (accuracy).
- Air Unit Upgrades: 'Afterburners' (Falcon speed), 'Advanced Munitions' (Osprey damage).
- Base Defenses: 'Reinforced Bunkers', 'Automated Turrets' for Watchtowers.
- Tactical Support: 'Orbital Scan' (reveals fog of war), 'Emergency Airdrop' (reinforcements).
Always balance economic growth with research, as advanced upgrades can be costly but game-changing.