So the ending of Earthbound always bothered me because it causes a paradox. The only way to by-pass such a thing is to either...
1. Have Time Traveler's Immunity
2. Be on some sort of drug and THINK something happened
3. You entered an Alternative Reality and destroyed a possible timeline.
Paula's prayers did their job, Gigyas was purged from the Earth and Buzz-Buzz's request would be finally fulfilled. With their journey at an end, they would all return to their normal lives.
The robotic bodies that were left behind to forever rot finally gave out as the Devil's Machine faded from existence due to a blinding light that consumed all.
They returned to Saturn Valley but what surprised them was that there was no one around except for a few confused Mr. Saturns who were freaking out about the kids suddenly waking up.
At first they groaned and stretched but it turned out they had been passed out after drinking some tea.
Poo asked for the year and they confirmed that they indeed came back to the right time. Looking around there was no Apple Kid or Dr. Andonuts so they teleported themselves to Dr. Andonut's lab.
Appearing there in the summer the snow had nearly made the place a damp wetland. They entered and saw Jeff's father with a schematic to grow fruit without it's peel.
Jeff greeted his father.
"Hi dad- I mean-" He stuttered but was interrupted.
"Hello son. There are donuts in the fridge." He continued to experiment with a plant in front of him by dropping some chemicals.
"What happened to the Phase Distorter Mach IV?" Jeff wondered looking around seeing there was a half fucntional UFO.
"That sounds like a piece of science fiction but it is interesting..." He said adding water to the plant.
The kids looked at each other alarmed. Even the screwy doctor was oblivious to one of his experiments.
"Say...Dad- I mean Dr. Andonuts, what were to happen say a paradox in time travel were to occur?"
"Simple," He said moving the plant into the sunlight. "Any events from before would cease to be."
Ness, Paula and Poo stared, they understood the implications but it explained why the Mr. Saturns didn't recognize them nor did Dr. Andonuts.
They saved the world but their adventure only existed to them but the only way to make sure was...
They knocked on the Minch residence and Picky answered.
"Hey Ness and friends." He smiled.
"Is Porky home?" Ness asked eager to peak his head into the doorway.
"Nope, he hasn't been home since you left to help that psychic girl who called you."
Ness thanked him and they went to the Happy Happy Village.
Paula got chills being there and Poo was on guard.
Ness entered the main house and talked to Mr. Carpainter.
"Why would I abduct a little girl? I say, I do say, that is mighty inappropriate."
The Polestar's commented that Paula called Ness to awaken his powers since she had dreams of meeting him. It made her blush but Ness didn't notice.
They talked to past people they've helped but the Runaway Five were still in debt. Monotoli was still a real-estate man. Mr. Spoon lacked his prize banana peel autohgraph and Apple Kid was still a shut-in and Ness lost all money he gained from killing snakes and crows with shades.
There was no crash site in either Threed or Summers and Poo was scolded for running away from the Kingdom.
Jeff returned to school where Tony asked why he ran away in the first place and Jeff had no idea and lied about meeting his estranged father. At best he assumed that they had taken the lives of their counter-parts in this new world and now had to live out ordinary lives in which only they remembered.
They didn't commit genocide to an alien race that hid behind space-suits. All was right with the world.
Except for one other who did as well but he was no longer in this time...
So yeah...Downer ending but if you think about it, there's no way they should have returned to their lives before Gigyas' influence on the Earth.