Adventure Mode: World of Light

Adventure Mode: World of Light is a game mode in Super Smash Bros. Ultimate, similar to Super Smash Bros. Melee’s Adventure Mode and Super Smash Bros. Brawl’s Adventure Mode. It was first revealed at the end of a Nintendo Direct on November 1, 2018.

Overview
On November 1, 2018, a Nintendo Direct ended with a cutscene that featured the entire roster of Super Smash Bros. characters going up against a mysterious foe known as Galeem with an army of Master Hands. They were all seemingly vaporized (except for Kirby who managed to escape on his Warp Star) along with the rest of the universe. Kirby then crash-landed on a mysterious planet and embarked on a mission to save everyone who are revealed to have been captured and cloned, with the help of Spirits.

Gameplay
The player starts with Kirby as the only fighter available in the party. The fighter travels in an overworld map where they encounter puppet fighters on their way, which are possessed by spirits. Once they are defeated, their spirit is obtained by the player, which can be equipped by the fighter. The fighter will also encounter other playable characters. Defeating them adds the fighter to the party.

Spirit Fights Conditions
Each individual Spirit Fight will involve some sort of condition that is themed after the Spirit that is possessing the puppet fighter.

Stat Buffs & Nerfs
Either the player or the enemy puppet fighter will have their stats increased or decreased during this specific fight. For example:
 * The enemy's side special has increased power
 * The enemy has super armor and is hard to launch or make flinch
 * The enemy's melee weapons have increased power
 * The enemy has super armor but moves slower
 * You constantly take minor damage

Repeating Temporary Powerup
The enemy will have a powerup that automatically activates and deactivates throughout the match after several seconds such as. For example:
 * The enemy is invisible
 * The enemy is metal

Permanent Item
The fighter will spawn with an item automatically equipped. If the fighter loses that item, a new one will spawn on the stage to compensate. For example:
 * The enemy starts the battle with a Killing Edge
 * The enemy starts the battle with a Lip's Stick
 * The enemy starts the battle with a Drill
 * Hostile assist trophies will appear
 * Normally this is a specific individual or set of Assist Trophies

Specific Tactic
The enemy mimics the personality of their Spirit by mimicking their fighting style. The AI will strictly commit to this rule with only occasional exceptions. For example:
 * The enemy favors side specials
 * The enemy favors grabs and throws
 * The enemy loves to taunt
 * The enemy tends to avoid conflict
 * The enemy is easily distracted by items

Special Smash
Not all fights will involve the standard stock or timed match; instead, it will include a special rule that will affect how the fight is played. For example:
 * Stamina Battle
 * Timed Stamina Battle
 * Defeat the main fighter to win
 * Certain items will appear in large numbers

Plot
The story begins with Fox leading the majority of the playable characters (both heroes and villains) against an incoming army of Master Hands (with Marth claiming that each of the fighters has to defeat about 10 Hands). Before the battle begins, the exteriors of the Master Hands disintegrate and the glowing cores are absorbed by a mysterious being known as Galeem.

However, Shulk realizes from a vision that Galeem set them up and the whole thing was a trap, but Shulk was too late to warn his allies about the outcome. A fully energized Galeem then creates the aiming beams of light that decimate every fighter they hit; regardless of their agility, power or defenses. Thankfully, Kirby is the only exception and manages to flee on his Warp Star. Galeem's magical light then quickly engulfs the world, its other characters, and eventually the entire universe.

Kirby then crashes on a mysterious planet and begins his journey to rescue his friends; who are revealed to have been captured by Galeem, who used a magical liquid metal to create replicas of their bodies. Galeem then forces the Spirits to possess these bodies to become their puppet fighter.

After gaining them, the fighters will go after Galeem, who, once you defeat him, ends up fighting a dark, demonic energy known as Dharkon.

The player will have three choices after this: two Bad endings, or the True ending. The Bad endings happen when you choose to fight either Galeem or Dharkon. If you fight Galeem, Dharkon will chain up Galeem, and overtake the universe, essentially changing the World of Light into a World of Dark, ending with Mario falling down, dead.

If you fought Dharkon, then Galeem would take over the universe with his light, vaporizing every fighter, similar to the opening cutscene, but on a larger scale.

The True ending will occur when you simply walk away from the conflict. If you do so, Galeem and Dharkon will fuse, and then you have to fight it. if victorious, the Spirits from the World of Light will float into the sky, happily return to their original worlds, forming a light that shines across the restored universe.

Trivia

 * According to the creator Masahiro Sakurai the reason why Kirby was selected as the starting protagonist in this mode is because his Warp Star has the ability to warp and that makes for the most believable reason that he would be the one to escape Galeem's attack. Sakurai also mentioned that he wanted the starting character to be simple and easy to use so Kirby was the obvious choice.