Celeste is a video game about a girl named Madeline climbing Celeste mountain.
First, Madeline almost dies because of a collapsing driveway ridge and is laughed at by the owner, Granny.
Then, Madeline explores an abandoned city. She makes it out of the city and sleeps by a fire.
After finding some ruins in a dream, Madeline releases the evil part of herself.
She is chased by that part of herself while exploring.
Next, Madeline cleans up a mess for a ghost hotel owner Mr. Oshiro, but gets chased when the evil part of herself angers him.
While cleaning up the mess, she runs into Theo, another person trying to climb the mountain. Theo warns Madeline to get out, but, obviously, Madeline doesn't.
After braving the wind of a narrow ridge and finding Granny there too, Madeline watches as Theo, who was with her, loses himself in a mysterious temple. After some exploring, trapping herself in a mirror, and surviving monster attacks, Madeline finds Theo and escapes.
After sleeping for a bit, Madeline wakes up outside the temple and uses feathers to keep moving up the mountain. The evil part of Madeline comes out, and Madeline says that it would be better if they went their separate ways.
Suddenly, Madeline is grabbed by a massive tentacle and falls to the bottom of the mountain.
She eventually finds the evil part of herself and fights her. They apologize and after a long trek, reach the summit together.
After coming back down the mountain to Granny's house, Madeline and the people she's met sit down to eat some strawberry pie. Madeline bakes a delicious pie, which everyone enjoys.
Madeline comes back to the Mountain later to explore the Core. It is really hot in there and has a lot of hazards, but Madeline makes it through by changing the temperature using a switch.
Granny dies, and Madeline mentally collapses. In a dream, she explores the moon in denial that a bird she's seen earlier is part of Granny. She eventually accepts that she is in denial, and frees the bird.
After waking up, Madeline goes on a Zoom call with Theo, and Theo asks why Madeline had seemed dead recently. Madeline says that it was because of Granny's death. Theo shows Madeline a picture of Granny and Theo's Grandfather climbing the mountain together.