Smash Run is a 3DS-exclusive mode--a 4-player, labyrinth-exploring, boost-collecting battle game.
First, the fighters enter a vast playing field.
There's a 5-minute time limit!
During these 5 minutes you'll explore the field, battle enemies, and collect boosts to power up.
There are 6 types of boosts - Speed, Jump, Attack, Special, Arms and Defense.
When the time limit is up, you'll carry the boosts you collected into battle.