The missile system
Specifications of an interplanetary missile:
hitpower ( basic ): 12.000 ( weapon tech will be included )
range: ((level of impulse drive * 2) -1) systems plus your own system.
velocity: constant, 30 seconds within your own system, 60 seconds for each further one.
workings:
First, the primary target will be hit. Hereof so many units will be destroyed as possible with the missiles hitpower.( the shields of the defensive units will be ignored, only the hull of them counts [ it can be improved by researching armor technology ]. ).
The hitpower, which doesn't last out for destroying any further units of the primary target, will be redirected to the other defensive units in the following order: Rocket Launchers -> Small Lasers -> Heavy Lasers -> Gauss Cannons -> Ion Cannons -> Plasma Cannons -> S. Shield Dome -> L. Shield Dome
an example:
Both your weapon tech and the target's armor tech are at level 0. That means that your interplanetary missile can cause 12.000 damage and a Plasma Cannon of the target can sustain 10.000, a Rocket Launcher 200.
Now your're shooting off a missile with the primary target "Plasma Cannon". On the target planet exist two Plasma Cannons and 30 Rockt Launchers when the missile arrives. The missils hits the planet and destroys with it's hitpower of 12.000 one Plasma Cannon, which can only sustain 10.000. The remaining 2.000 hitpower doesn't last out for the destruction of the second Plasma Cannon, it will be redirected to the Rocket Launchers. 2000 / 200 = 10 of them will be destroyed.
There exists a possibility how you can defend yourself against an missile attack for a reasonable price. Construct anti-ballistic missiles. These missiles will be fired at approaching interplanetary missiles automatically and will destroy them before they hit your planet.