In the archive, the Saves folder – drop it into the game folder (or another place – depending on the release).
So, in each chapter you need to find a hidden blue heart and a cassette (8 hearts, 8 cassettes).
The cassette opens a more difficult mode for the chapter: B-Side, in which you need to find a red heart (+8 hearts).
Celeste: Save Game (199 strawberries / 24 hearts / retro) Free Download
After completing the game, the C-Side mode opens – even more difficult, in which you need to find 8 golden hearts (+ 8 hearts).
To open the 8th chapter, you need at least 4 hearts.
To open the B-Side for Chapter 8, you need to collect 15 hearts in the previous chapters.
To open the C-Side for Chapter 8, you need to collect 23 hearts in the previous chapters.
After receiving the first 16 hearts, for each chapter passed, the golden strawberry mode opens – you need to pick it up at the beginning of the level and bring it to the end, never dying. In total, you can collect +24 bonus strawberries (8 chapters * 3 modes), as a result, the strawberry counter will show 199/175.