New details have been released about the single player element of Super Smash Bros. Brawl, "The Subspace Emissary".
"The Subspace Emissary" storyline introduces a force of formless enemies called the Subspace Army. They are ruled by their commander, the Ancient Minister.
Their objective is to cut apart the world and carry it into Subspace. They use what are called Subspace Bombs to do so.
When a Subspace Bomb explodes, a section of the world gets excised and swallowed by Subspace.
This is a new, never-before-seen form of aggression...but now is no time to stop and stare. Everyone, everywhere, is beginning to move against it.