From the Steam Store page:
Help Madeline survive her inner demons on her journey to the top of Celeste Mountain, in this super-tight, hand-crafted platformer from the creators of multiplayer classic TowerFall.

A narrative-driven, single-player adventure like mom used to make, with a charming cast of characters and a touching story of self-discovery
A massive mountain teeming with 700+ screens of hardcore platforming challenges and devious secrets
Brutal B-side chapters to unlock, built for only the bravest mountaineers
IGF “Excellence in Audio” finalist, with over 2 hours of original music led by dazzling live piano and catchy synth beats
Pie
The controls are simple and accessible - simply jump, air-dash, and climb - but with layers of expressive depth to master, where every death is a lesson. Lightning-fast respawns keep you climbing as you uncover the mysteries of the mountain and brave its many perils.

This is it, Madeline. Just breathe. You can do this.