The following is the entire story of Mother 1. Don't play it, the tech limitations of the NES hamper it, and there are a few game-breaking glitches that may pop up.
[spoiler]Ninten woke up one day with his house attacking him. He defeated them, then found his Great Grandfather's Diary, who said that he was a destined child. He found part of an old melody in a music box. He found another part from a bird in a cemetary.
Ninten then came across the magical land of Magicant, where he was welcome. There, Queen Mary told him to find all 8 parts of the melody, because she couldn't sing it, and wanted to hear it again.
He found a third part of the melody from a singing monkey.
He came across a nerd everyone picked on called Lloyd, whom he made friends with.
He came across a girl called Ann who simply knew it was her destiny to travel with Ninten. The trio found the fourth melody in a piano in a haunted house. They found the fifth melody in a cactus in the desert. The sixth melody was given to them by a dragon in Magicant.
They traveled to the city of Ellay where they beat down a gang called the BBs, and their boss, Teddy, asked to travel with them to avenge his parents, whom were murdered. Teddy told Lloyd to take a break, he'd take over for him.
In the city of Youngstown, children everywhere beg and plead for you to get their moms and dads back, who are being held at Mt Itoi.
At Mt Itoi, you are assaulted by a gigantic robot. Lloyd comes with a tank and saves you. Teddy is wounded, so Lloyd takes his place.
You go to the lake on Mt Itoi, where you find your great grandfather's lab, and a robot named EVE who is sworn to protect you.
You climd Mt Itoi where the robot from earlier attacks you. It destroys EVE, but EVE's explosion kills it. EVE gives you the seventh melody, it's mission fufilled.
The 8th Melody is given to you from a strange stone that has "XX" carved in it that speaks telepathically to you. You return to Magicant and sing the melody to Queen Mary.
Queen Mary is your Great Grandmother, who begins sobbing, saying that Giegue is behind the whole mess, and that she raised Giegue when it was a child.
Magicant dissolves. It was nothing more than an illusion held together by the ghost of your Great Grandmother Mary.
You return to the XX Stone, which is revealed to be your Great Grandfather's gravestone. It was him who spoke to you earlier.
You go foward to confront Giegue, who attacks you in an incomprehensible nature. He says he will wipe out all of humanity, and then offers Ninten a place in his ship, spared from the slaughter. Ninten refuses.
You sing the melody to Giegue, forcing him to retreat as he can't reconcile the pleasant memories of his 'youth' with the desire to kill everyone. He swears to return one day.
Giygas is Giegue after he has lost what little humanity remains in him.[/spoiler]