I like the command points.
Lets see what small ideas I can contribute:
-single shipcounters are like in starmada the core of the counters. they should have values like missile, beam, speed, defense, size, specials etc. the best would be to find formulas which convert starmada ships to the simpler starmada invasion format.
-ships should be organizeable in task forces. A player has to preplot the movement of his task forces on a sheet of paper similar to starmada. Preplotting is not just "move here or here". Its also assigning a specific mission to a task force.
Possible missions could be:
-hit and run
-probe
-engage and destroy
-engage and board
-invade
-bombard planet
-patrol
-resupply
-escort
etc.
The skillful assigning of ships to a task force to accomplish the missions and the mission system itself could be the core engine and the most interesting part of the game.
The playing area in space
Hexes? Squares? or maybe something completely different? I am not sure if hexes are that ideal for portraying a solar system. The distances in it could be vast and even with some "tweaking" its not easy. (eg. inner and outer ring of planets in the sol system)
So maybe I would like to see for an alternative way to portray the map board. (I am just not sure which one:))
The playing are on planets
-could be hexes I think, planets could be portrayed abstractly in a classical way (circles around a central hex) like 1 hex is an asteroid, 7 hexes is a moon, 19 hexes is a small planet and so on. Or the map of planets could also be bigger and more complicated. On the hexes the ground units move. Ground units could be from company to regiment or even divisions. There could be different types of unit like jump troops, grav armor or marines, planetary militia or space defense batteries.
playing out planetary combat could be unlike mission assigning played out sequentially similar to fighter combat in starmada without preplotting the moves.
Different terrains (urban, difficult, normal, ocean, impassable, subterranean, rifts etc.) would also be fine, or even different atmospheres, gravity or temperature.