LightTale is an Undertale Alternate Universe (AU) where all of the residents of Undertale have the power of light. Frisk (the Protagonist) can choose whether to kill all or spare everyone. Same concept as you would have in Undertale. When a resident from LightTale dies, A part of the CORE gets darker. If the CORE is completely dark (if you have killed everyone) you cannot see through your journey. All of the residents of LightTale will try to reason with you before they fight you. But there are two individuals that will try to kill you. And that is Sans and Papyrus. They've been filled with darkness, and will try to kill you in anyway they can. If you're doing a genocide route they will help you and you three will cross the barrier with all of your souls mixed together.
Creator of this AU is James0330