You have too many good ideas. Have you considered putting them all in a pot and making Space Pirate Strike Witch Mechs RTD?
Ha. Hahaha, ha. Ha. HA. BWAHAHAHAHAHAHA.
CHALLENGE ACCEPTED.A game where 95% of the earth is water, so wars are fought in giant aerial mecha (similar to tanks) and PAC/MAN (Personal Air Combat / Marco Active Network) suits. (similar to common forces, but Strike Witches style.) Command Center is basically a GIGANTIC ship, capable of launching all sorts of aircraft, and serves as a bay for other ships, most of which have or charge from perpetual engines. Ships come in three main components:
"Masts": Crucial parts of the ship. So long as the ship retains at least one, she can still function, but she loses speed for every one lost. Most are engines.
Weaponry: Intership weaponry ranging from missiles to railguns. Ships are given ratings rather than definite amounts of weapons, based on weapon clusters that have the power to reliably destroy ship components.
Cargo Space: How many things the ship can hold, including crew space.
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Combat is simple, depending in what you're piloting. The common suit comes in many variants, and can be upgraded or mixed with other types of suits to give you various abilities in combat. Some specialize in taking out mecha, such as heavy weapons proficiency or abilities from the Electronic Warfare kits. Others are built to take out enemy forces, such as Fighters, and those oriented to destroy enemy bases and naval units, such as Bombers or Antisubmarine kits.
In this form, combat is done as duelling d6s, including whatever abilities come into play, effected by the current enviroment, and equipped weapon/armor.
When piloting an aerial mecha, combat is done as part rock/paper/scissors and part 3-stat base, or maybe something else, there really should be a way to balance that but I have yet to find it. Attacks against groups of soldiers can be done with certain weapons or loadouts, damaging them as a group or applying an effect as a whole, but are ineffective at precise attacks. Mecha vs Mecha is the most common. Mecha can more easily attack naval emplacements, making them more effective vs enemy ships than enemy soldiers.
Naval units can also be sent out. Many are equipped with weapons that excel in taking out large numbers of soldiers, but many do not have the accuracy or power to destroy a mecha efficiently.
Actually, might apply the same combat system to everything and assign bonuses based on who's attacking who.To repair a Mothership, she must idle in non-contested waters to repair one "mast" at a time, away from battle, or dock at her tiny home island for repairs (two per turn). Each nation's land is very small, but has strong defenses and orbital elevators- most people live in space or on large ships.
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Roughly 1 in 8 people capable of using the mecha or PAC/MAN suits, which tap into the user's inner energy, find themselves capable of "magic" feats, by harnessing said energy better than any other.
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Large scale combat is a scary thing- PCs will act as leaders of squadrons, which are 100 units each, or Mecha Pilots, or be on board a Naval Unit. For all NPC controlled units, combat is vastly simplified to duelling D6s, without bonuses, but end damage is influenced by the unit RPS. A 100 man squad gets a 1 and a naval unit gets a 6? They're wiped out. If the squad got the 6 and the naval unit a 1, the naval unit would take serious damage but still be functional enough to attack next turn.
An NPC unit attacking a PC unit is calculated as if the NPC unit was a PC unit, for balance reasons.
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There are other types of fighting, aside from the Mothership VS Mothership combat. You may fly a small platoon of Stealth/Reconnaissance units over an enemy force and try to escape, for instance.
Sometimes, you'll have to defend your home island from others.
Occasionally, you'll even have to deal with orbital weaponry. Sometimes, you'll deal with such weaponry breaking and re-entering, and you'll need to clean up the debris- as, if sea life takes a hit, so does the entire food stock of the planet, and you may be attacked or helped by others. Every so often you'll get to go up the orbital elevators and have peace talks, time off, or god knows what.
I also really like that 1d4(d4), and may have noncombat actions use them.