Alright, I managed to play a game of Astropolis over my local wargame association, together with a Warhammer Fantasy Battle veteran nonetheless. We had fun, but there's definitly some tuning to do.

1. At one point, one of his ranged units got stuck in melee combat with my heavy weapon units. He had no reason to active and attack cause it would have resulted only in a unfavorable combat as I had priority to fight. The game needs a Retreat action, even if it costs some wounds/losses.
2. Nobody used the Ready action. I'm starting to think it's a bit pointless. I could do that in Move and Shoot, if you don't shoot, you become Ready. Also I could do that if a ranged unit is Ready, it can react to a charge and shoot before contact.
3. I need to change either the units Heavy/Light names or the Heavy/Light adjectives from the weapons, it gets confusing pretty quickly.
4. A deck per player. It gets messy with just one deck to draw from and shuffling.
5. Buff heavy infantry units , probably by analyzing some bell curves of the decks drawing.  Also, it makes almost no sense to give them ranged weapons.
6. Maybe add some spice for rank and flank combat, as you should play with the card-bases.
7. Cumulative points objective. It's probably more fun.
8. Ditch the leader as a unit and transform it into a keyword to give to any other type of unit. They were pretty tame and useless as units, so might as well go with 5 units and have one of them being buffed.