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.
In addition to standard Smash matches, you can try Reflect Smash, where you automatically reflect all projectiles, High-Launch Smash, where every blow will send you flying, Climb!, where you see how high you can climb within the given time, and many other smash varieties.
It's not like players will be in parallel universes battling each other directly.
From time to time, events will occur. All players will be subject to similar conditions and they will use their techniques to power up and proceed.
You can carry equippable items with you, and you can use them to improve your performance in Smash Run.
Characters from a variety of games will appear as enemies.
An ever-changing cast of enemy characters will be randomly placed. More powerful enemies drop lots of boost items. They are also more likely to drop custom parts and other rare items.