The Subspace Emissary story tells the story of a mysterious invasion that takes place in the world of Smash Bros., where all the characters involved must band together to combat the invading forces in order to avoid the imminent (but unknown) danger. Yes, it has a fairly generic plot, but the gameplay holds up. It's a 2D side scrolling adventure the feels like it came from the days of old. It starts most of the characters in Brawl. Link and Mario team up like never before. Samus and Pikachu fight one of Samus' biggest enemies. In the end, you all fight the omnipotent evil together.
It's a really great premise, but, by the end a few things hold it back from really reaching the pedestal worthy of its star power. The SSE mode is a really great addition to Brawl, and an impressive evolution of the adventure mode from Melee, but some glaring problems stand out.
Nevertheless, MTV Multiplayer's Jason Cipriano wants a sequel.