I feel like planetary assaults could be expanded. Right now its pretty generic. Just show up at a planet, bombard it then take it over.
This is what I was thinking, and would probably need to be in an expansion:
1. Planetary Assault Supply: Acts just like fleet supply.
2. Added Research Tree: Add a block for assault forces where you can research increased Planetary Assault Supply, and other tech upgrades for planetary assault forces
3. Planetary Assault Forces: Planetary Assault ships to hold the units mentioned in this paragraph. In addition, add a component for capital ships to carry assault forces. Standard Infantry, Commando's, Light Assault vehicles, Heavy Vehicles (Tank, Artillery) and anti-air. These different units have different supply costs, adds a paper-scissors-rock element. Shield Generator unit: Protects only your ground forces from orbital bombardment, however, if the planetary shield generator is gone, and the whole planet is being targetted for bombardment, then once planet health is gone your forces die too, but the planet suffers negative affects from whole planet bombardment. (see Bombardment section below)
4. Air Support: Attack Craft: Provides air cover for landing your forces, or if an enemy doesnt have Air support in a landing but you have it for defense, then it basically shoots down all the landing craft. Give an option to order Carrier fighters/bombers to provide support on landing units on a planet. Adds a stragetic element to counter ground units, unless there is AA around. This can also be specialized with fighters, bombers, and hybrid attack-fighters.
5. Bombardment: Should cause permanent and temporary damage to planets resources, over health, resource outputs etc.. This way if your attacking an enemy and do not care about taking over the planet, just wiping it out and causing detrimental damage to the planet so its not as good to colonize from others. Can include a targetted bombardment on just planetary defense forces without causing damage to the planet.
This would help add depth to taking over enemy systems. So if your attacking a resource rich planet with a Starbase with Plantery shields, and a mixed composition of planetary defense forces, it makes you think twice of committing your forces, or make you have to gather a large force to take over one system. Will add elements of strategy to taking over a system vs just bombarding it with an overwhelming fleet with how the current system works.
Just felt this was an area that could be improved on. Its an element of other Space RTS games that I feel is missing from Sins.