Launch your Death Star and cast a hypersonic thunderbolts from space that will only kill biters, spawners and worms in a large radius.
Mods introducing new content into the game.
New ways to deal with enemies, be it attack or defense.
Just destroying aliens seems too weak, as a death star? Consider destroying the terrain too? (Say converting land terrain to "water" and "deep-water"...)
hehehe.. It has to turn all the planet into pieces! ehhehe
But thats a real great idea, transform the ground... make holes, cliffs , water... :)