Not many people realize this, but Celeste has quite the history behind it. Starting as a small project during a game jam, creator Matt Thorson later expanded the game into the release we now know and love. Obviously there are references strewn about the experience to remind us of the original prototype, but you can also play that original version in all of its indie glory from within the new game.
Accessing it is as simple as finding the Easter Egg within the title and walking up to an old PC. From there, you can play out the entire prototype, if you so wish. I love when developers do things like this; I'm a huge proponent of preserving video game history, so this just makes me smile.
via destructoid https://www.destructoid.com/you-can-enjoy-the-original-celeste-in-the-new-game-485182.phtml