Cheat Mode

Cheat Mode is a hidden feature in Celeste that can unlock every chapter in the game, and other features such as Golden Strawberries, B-Sides and C-Sides, as well as opening the Heart Gates without the need of any Crystal Hearts. Saves with this mode enabled will have a small green stamp with the "cheat mode" text on it. This mode also doesn't change the player's berry or heart counts.

Enabling Cheat Mode
Cheat Mode can be enabled in two ways, with or without Debug Mode. The first way is to unlock it from the Prologue chapter. In order to make it work, the player has to go to the left in Prologue chapter, where the intro car can be found and perform a combination of inputs shown below:

Left, Right, Journal, Grab, Up, Up, Down, Left, Grab, Jump

Or, with default controls:
 * Keyboard: Left, Right, Tab, Z, Up, Up, Down, Left, Z, C 
 * Controller: Left, Right, LT, RT, Up, Up, Down, Left, RT, A
 * Switch: Left, Right, ZL, ZR, Up, Up, Down, Left, ZR, A

In order to make this command work, the player has to perform the combination in the intro car room. If they by any means go outside the room by accident or not, the mode won't be activated.

Debug Mode method
If the player has modified their savefile and have Debug Mode enabled, a command console can be enabled with the "." or "~" keys. Cheat Mode can be enabled that way by simply typing "cheat" in the console. After that it can be closed by typing the "q" command, and Cheat Mode should be unlocked afterwards.

Cheat Mode usages
Cheat Mode unlocks every chapter and their alternate sides, as well as giving the player access to everything without the need to unlock anything. This mode is very useful for speedrunners or players who need to practice a specific chapter on a separate save file. Cheat Mode also allows players to run miscalleanous categories such as All B/C-Sides, All Hearts, etc. without the need of unlocking everything beforehand.