The two features I'd like to see in an Amiga game:
1. A campaign editor like in Starcraft, with optional "simple mode" to quickly create a "just kill your enemy" map.
2. Easily replacable graphics for user customization. That could be difficult with 3d graphics though... maybe a texure editor option?
Gameplay suggestions:
Maybe have certain units lose functionality as they become damaged.
An army morale counter would add an interesting element as well.
Allowing ground troops to take over vehicles from enemy crews.
Varying damage based on how much cover units have
