As someone who loves the strategy and tactical when it comes to finding, buying, building, researching items I always love more reasons to collect stuff to use in battle. All of these can be tiered with research, mfg, faction status and equipment.
It may be fun to add technology for shields.
The early game perhaps a physical shield can be carried that helps to deflect kinetic hits but then you are limited to melee or pistol weapons.
This could advance to the following:
- Deployable Kinetic barriers (unmovable once deployed)
- Deployable Energy or Organic barriers
- Powered personal shields
- Motion Sensors
- Recon Drones / Battlefield Camera
- Deployable Turrets
- Mist Repulsion
- Enemy attract or distraction
Air Drops (May require specific unit or equipment to activate)
I see air drops being restricted by expense, availability, and number of uses etc.
- Medical Supply drop
- Ammo / Weapon drop
- Air support (fly by, single shot type of support, expensive and only if you build a drone/hired pilot etc.)
- Reinforcements? Perhaps based on how many units you have fielded that are in range and the aircraft available. Also, something that needs to be set up during mission planning. If you have an extra aircraft, in range and extra healthy troops they can be added to the mission as reinforcements. Could be costly but would give reasons to invest money in additional aircraft.
Some of this, of course, could be hard to balance in the game to avoid overpowering force but definitely would add some difference to the game to set itself apart.