Undertale is a great game.
Its an indie game in a simple pixel style. The monster designs are wacky and fun.
The Story is very well written and the characters are awesome.
Its also a bit heartbreaking.
If you want to play buy the game here LINK
If you don't have time to play there are several Lets Play videos on Youtube right now.

This is Toriel, you first meet her in the "Prologue" of the game. She's so sweet and is known in the fandom as Goatmom

Undertale @ Toby Fox

PS. I recommend you reset the game only when you finish the game first.