Many years ago, two races dominated the Earth: humans and monsters. One day, a war began between them, known as the Great War. After a long and brutal battle, humans emerged victorious, and the monsters were sealed underground by a magical spell.
Years after the Great War, monsters adapted and began building their own cities and societies beneath the surface, trying to rebuild their lives underground, while still holding onto the dream that one day they could return to the surface.
But peace did not last forever… Red ecuante flowers began appearing throughout the Underground. At first, they seemed harmless, and many ignored them. However, they spread quickly and soon became impossible to overlook. Any monster who came into contact with them became infected by a strange disease that initially appeared mild—almost like a common illness.
Hours later, the infected monsters became aggressive and ravenous, attacking anyone without control. Chaos spread through the Underground at a terrifying speed.
The monsters who were not infected soon realized they would have to make difficult choices to survive. Those who were bitten or scratched by the infected began to transform as well, losing all reason. The struggle for survival forced the remaining monsters to face friends and loved ones who had been infected.
The Underground, once full of life, fell completely into chaos. Now, only one rule remains: survive.
You begin your journey by falling into this unknown world. As you stand up and take control of Frisk, a message appears:
"You try to move, still feeling the pain of the fall… pain, pain. You ignore it and look around. You don’t know where you are, but you feel that something in this place is wrong… and it shouldn’t be this way."
The dialogue ends, and the gameplay begins normally. However, the environment already shows signs of what happened: cracks in the ground and red flowers scattered across certain areas.
Upon reaching Flowey’s room, he is standing with his back turned. As you approach, he startles:
"Ahhhhh! S-sorry… you’re human, right?"
He tries to act normal, but it’s clear that he is scared. He continues:
"I-I-It must have been… a f-f-fall…"
Before he can finish, a very loud noise echoes. Flowey panics and disappears into the ground.
Then, something appears that makes Frisk step back: Toriel—but infected. Her body is grotesquely affected by the red flowers. She looks around, glances at Frisk for a moment, and then walks away.
"You feel fear. You don’t know what that thing was, and you begin to wonder… what is happening here?"