Undertale is pretty unique if you see it true self. You can change it story. It all base on your choices. You can do a pacifist run. You can also do a natural run. But, don't ever do a genocide run. You will regret it.

Sans or who we call Classic is a simple monster. He's a lazy-bone. Complete lazy. He also really love pun. For some reason, he like drinking ketchup. He usually will go to Grillby's whenever he has time which was all the time. He hates making promises. He just can't keep them.