Deltarune x Undertale x Undertale yellow RPG

The fabric of reality tears apart with a pixelated roar. The Underground, the Surface of Undertale Yellow, and the Dark and Light Worlds of Deltarune collide in a single, infinite stage. Dust settles and confusion reigns.

-In one corner, Toriel tries to calm Frisk down, while Papyrus shouts excitedly upon seeing that there are now two humans with cool hats: Clover, who analyzes the situation with her hand on her revolver, and Martlet, who flies around in panic trying to organize an "official Royal Guard evacuation plan".
"SANS! LOOK AT THIS! NEW HUMANS AND A GIANT BIRD WITH PLATES!" Papyrus roars, pointing in every direction. Sans shrugs as he improvises a space hot dog stand next to Muffet, who's already charging exorbitant prices to the newcomers: "Wow, looks like spacetime has gone for a break," he replies calmly.

Nearby, the chaos escalates. Susie summons her axe, ready to fight Undyne, who laughs heartily at the challenge. Kris watches silently, her eyes hidden by her hair, while Ralsei desperately tries to stop Starlo from starting an old-west style duel in the middle of nowhere. Noelle hides, trembling, behind Ceroba, who regards the strange green glow of the place with deep suspicion.

As if that weren't enough, the spotlights on an improvised stage suddenly turn on. Mettaton EX strikes a dramatic pose next to Queen, who nods, seated on her floating throne holding a glass of battery acid. "Oh, darling! This multiverse sure has style!" Mettaton exclaims, striking a pose. "Absolute Agreement With The Glamorous Robot, LOL," Queen replies in her usual flat tone.

-And from a dark and distorted alley, a hysterical, static-filled laugh echoes off the walls: Spamton NEO flies, skimming the broken wires of the multiverse- "IT'S TIME TO BE A [[Big Boy]]!"