Agree that MSP (for all units) and Sorium (for vehicles/aircraft) make sense for ground units rather than a separate resource type . I'll probably have logistic units 'carry' supplies that can be used by ground units, or have some inherent capability. This would be at a low level normally but much higher during combat. Vehicles without fuel would act only on defence and without any mobility bonus.
This offers the option for limited simulation of supply chains. Presume 4 'places' for supply, formation (Battalion), Brigade, Division, Stockpile. Logistics units can draw supplies from/send supplies to one level higher at a high degree of efficiency, but efficiency drops fast at 2 and 3 levels to keep Battalion supply units from easily avoiding the supply chain mechanic, and logistics units attached to Brigade and Division commands have larger or much larger supply storage capacity that lower level commands can draw supply from for their formations, but do not have greater transportation capacity. This means that part of army design will be determining how much supply transport and storage capacity you want.
Of course, if that is too much or not fun as a mechanic make it a 1 layer thing instead where the efficiency is static.
I know there are ordnance, fuel and general cargo specific rates for cargo transfers, but is there something similar for Maintenance Supply Points? It'd be kinda odd to have to deal with fuel transfer rates for ground forces, and sufficiently expansive armies are going to drain a lot of fuel, but be able to just drop 10 kilotons worth of MSP straight on planet in an instant.
I'd also encourage reconsidering not using a separate supply point mechanic for ground forces; life support/crew space kind of covers things like food supply for crew on board ships, even if you can cheese it at the cost of horrible morale. Ground forces though have no such system in place, but could be simulated through a ground supply point mechanic that's comparatively heavy in cash costs, unlike normal production which requires money equal to mineral costs ground supply point could cost some multiple of that.
Then again, while Aurora VB6 ground forces cost money to maintain, crew on board ships don't.
The 'fortification level' of a ground unit will act as a divisor on the chance to hit. So fortification level 3 will mean all to-hit chances against that unit are divisible by 3. This will also be true against ships attacking from orbit (more on that in a future post). Fortification level does not affect armour penetration or damage.
Any infantry or static unit will be able to fortify itself to level 3 over time without assistance. Vehicles will be able to fortify to level 2 (although this will negate their mobility bonus it would avoid any fuel use). Super-heavy Vehicles will be able to fortify to level 1.5. Aircraft will not be able to fortify.
Combat Engineers will be able to increase the fortification level of other units over time. Up to level 3 for vehicles and up to level 5 for infantry & static. (I may add some additional fortification bonuses for infantry/static depending on terrain). Combat Engineers will be also able to reduce hostile fortification levels over time.
If a unit chooses to attack, it will lose any fortification bonus. However, you will be able to attack with selected units and leave others in place.
More details later on how long it takes to fortify.
Are all units equally likely to be hit, or do certain sizes, size groups or base units have different odds of being hit?
Because that will influence whether or not a 20% chance of being hit when fortified is a good deal for infantry. Right now the odds are rather horrifyingly against anything with armour for unarmoured infantry, even with specialized weapons.
Then again, that could be a good argument not to ever bring your entirely unarmoured cheap as can be garrison infantry onto a battlefield. They
will die, unlike even light infantry which sports an armour rating of 1.
Also, unless fortification level is an integer number Bombardment weapons should erode fortification, heavier weapons of course doing more damage. If fortification level is an integer number Bombardment weapons should have a (low) chance of lowering fortifaction levels. Either way, Combat Engineers should be a much more efficient way to lower enemy fortification levels.
Units that are fortifying should probably use slightly more supplies compared to units that are fortified. Construction Engineers, if they are still a thing, should probably have a similar ability to strengthen fortifications, possibly to a greater extent or faster than Combat Engineers.
EDIT: Note; Fortification level 1 does nothing. Not sure if that's intended.
