Undertale Yellow was developed by a group of crazy fans of the Undertale game series. Embark on an adventure exploring a colorful world and adorable characters.

Hidden story

Undertale Yellow revolves around the main character W.D. Gaster, a mysterious scientist in the world of Undertale. Gaster is a genius scientist and department head of the Monster Kingdom. He learns about the power of SOUL and the magical ingredient known as Yellow Essence. However, during his research, Gaster encountered troubles and faced mysterious events.

Gaster's to-do tasks

Explore new worlds

Explore new lands in the world of Undertale, from dense forests to deep caves. Learn about the environment, interact with characters and search for hidden treasures.

Meet new characters

You will meet familiar characters like Papyrus, Sans and Flowey, along with new characters. Talk to them, help them or face the challenges they pose.

Fight monsters

Engage in battles with fearsome monsters. Use your fighting abilities and tactics to overcome these battles and protect yourself. Monsters to note:

Flicker: A flexible monster, capable of disappearing and appearing suddenly. Flicker attacks by creating energy beams and attacking from afar.
Scorch: A monster that takes the form of a small dragon. Scorch has the ability to breathe fire and create dangerous explosions. You must be careful to avoid its attacks.
Echo: The monster has the ability to copy itself and create dangerous clones. You must learn how to distinguish between a copy and the real thing in order to attack the right target.
Gloom: A mysterious monster that takes the form of a mysterious girl with the ability to create dark energy fields. Gloom attacks by sending out powerful magical attacks.
Blight: A large and ferocious monster, Blight has the ability to manipulate trees and the surrounding environment to attack the player. You must find a way to avoid Blight's attacks and attack its weak point.