SDI Program

The SDI Program is a shield you fund. It answers three things, and only these three: missiles fired at you from another planet, and the jets and bombers of a strike arriving from one. It does nothing against a neighbor on your own planet — not their army, and not their nuclear, chemical or biological missiles.

At full strength it turns aside about half the missiles aimed at you, takes 30% off an arriving realm's jets and 20% off its bombers. At half strength it does half of each. Only a strike aimed at you alone meets your shield; a group attack goes through it even when you are one of its named targets.

How strong it is

Strength depends on the funding and on how many regions you hold. The same funding gives a large realm a weaker shield than a small one, and each region you capture makes your own shield thinner. Each further percent of strength costs more than the one before.

Strength stops at 100%, but the program still takes gold past that point. The extra keeps the shield at 100% while you take more land. It also adds to the upkeep.

Funding it

The program is a pot of gold, not something you buy once. Each turn you may add up to a set amount: a fifth of what is already in the pot, and never less than 250,000 gold. Gold goes in only in whole thousands.

That amount is your allowance for the whole turn. Leaving the screen and coming back does not give you a second one.

So a shield takes many turns to build, however rich you are. You cannot buy one the turn you need it, so start early if you expect missiles.

Paying for it

Every turn the program asks for 4% of its total funding as upkeep, in the maintenance prompts, after your regions and before the Queen's tax.

Pay it in full. If you pay short, the program shrinks to what you did pay for, and the shield weakens with it. A large pot is a large bill every turn, so grow it at a pace your income can carry.