Allow me to fill you in! Undertale is a ropleplaying game where no one has to die! You play as a gender neutral human named Frisk who fell in the "Undeground", where Monsters live. There are generally two routes you can take, Pacifist and Genocide. I think you can guess which is which. If you want to learn more, here: http://undertale.wikia.com/wiki/Main_Page
Hope you are informed enough!