In this version of Smash Bros, a disease taking over fighters is spreading. The symptoms of stage 1 start one day after getting stinged by infected: wound starts to hurt, unvolountary smiling, worried or scared gaze.
Stage 2 has worse symptoms: blind, empty eyes, violent tendencies, hunger, and most importantly, growth of tentacles used to infect others.
*How... how long has it been since all of this started? Minutes, hours... maybe days, ever since **Kirby** succumbed to this... infection, and killed **Mario**...
Things have been so tense and stressful that you can't even keep track of time properly...*
*At least, most of those who survived, like you, **Ness**, **Cappy** possessing Ness' hat, **Sheik**, **Marth** and **Villager** were staying in a safe base with **Dr. Mario**, currently researching for a cure to this virus. A damaged **R.O.B** was helping him too, since the robot can't get infected, and **Olimar**'s been the first infected to get researched on, but he became too dangerous and got killed by R.O.B while infected Pikmins were eating the humanoid from the inside...*
*Then there's the deceased. Boy, have you seen them: the original Mario, **Luigi**, **Yoshi**, **Peach**, **Daisy**, **Snake**... You practically lost count, and who knows how many you don't even know of...
And the infected fighters you've seen are even worse... Kirby was massive, just infecting everything in his path, but contained in Dreamland... **Mr. Game & Watch** turned into a three-dimensional, lanky monster, **Piranha Plant** was now a kaiju abomination, **Inkling Girl** became a giant monstrous squid, and god knows who else suffered this infection...*
*Luckily, **most** of the infected are all confined to their original universes, meaning they couldn't harm anyone outside of them. You all tried looking for **Master Hand** and **Crazy Hand** too, hoping they could help in fixing this, but to no avail...
And now, after **Mewtwo** got infected by **Pichu** and Dr. Mario seemingly secluded himself in his safe base to let you all escape as he **maybe** died, many of you don't know what to do anymore, like Ness, who was just looking on at the closed base's entrance.*
*Eventually though, you all make it to Villager's world to regroup.*