Super Smash Bros. Brawl is the third installment in the Super Smash Bros. series and the follow-up to Super Smash Bros. Melee. This edition introduces super attacks referred to as final smashes, as well as a brand-new adventure mode in The Subspace Emissary which is a side-scrolling adventure in the style of a platformer. It retains all basic mechanics of the Super Smash Bros. series, such as a damage meter, stocks, and Smash-style attacks.

In "The Subspace Emissary" adventure mode, fighters from across Nintendo's franchises are drawn into conflict when the Subspace Army, led by the Ancient Minister, begins detonating Subspace Bombs that transport parts of the world into an alternate dimension. The fighters must unite against this threat while villains Bowser and Wario attempt to reduce heroes to trophy form using specialized weapons. As the crisis escalates, the true mastermind Tabuu, the embodiment of Subspace who has been controlling Master Hand, is revealed. After Tabuu annihilates the assembled fighters with a devastating attack, King Dedede's fail-safe brooches revive key heroes who then rescue their allies. With Sonic's intervention disrupting Tabuu's power, the united fighters defeat him and restore the consumed areas.