I generally like the selection of the ground units (some artwork and uniqueness issues notwithstanding), but the game needs more air units. Right now, all we have is a scout, an air-to-air fighter and a heavy bomber. The heavy bomber is expensive and gets shot down by AA fairly easily. And since the AI rarely builds bombers, we don't need to build air to air fighters.

Some suggestions - 1) a Tier 1 gunship, capable of doing decent damage against Tier 1 ground units (might need to add a Tier 1 anti-air ground unit as a counter) 2) Tier 2/3 bomber that drops a non-conventional bomb, maybe something like an EMP that temporarily disables or freezes units 3) Tier 2/3 advanced scout that has very long sight range, allows ground artillery units to fire beyond their own limited visual range 

The ground battles are shaping up well. We just need a few more air units to add an air strategy element to the game. Adding more air units will make maps much more interesting and dynamic.