UWE need a story to tell the "not-currently-involved" to make NS2 sound awesome. I don´t think i would buy a game with the description: A RTS/FPS game. You can kill aliens!
They need something epic but still not a rip off...... Maybe its a new planet that they are trying to build a colony on. And the aliens are the new planets wildlife! Or a alien alliance called the covernant that is trying to wipe out the humans! Or the aliens are undead under the lich kings control! Or maybe the aliens are from the nazi/ku kulx/communism/ninja/shoop da whoop/mingebag clan of evil!
Lets just try to figure out a story and hope that it will be in the game (and that i get all the credit for it)