CelesteTAS is a mod used by the Celeste community to create and playback TASes of Celeste (using .tas files). It additionally comes with Celeste Studio, a text editor designed to make TASing easy and convenient. It is available on Windows, Linux and macOS, and is run by using the Everest Mod Loader.

To install Everest, follow the instructions found on the official website here: https://everestapi.github.io/#installing-everest

To install CelesteTAS itself, follow the instructions found on the GitHub here: https://github.com/EverestAPI/CelesteTAS-EverestInterop/blob/master/README.md

For general documentation on how to use CelesteTAS and Celeste Studio, as well as the details of the .tas file format, consult the wiki on the official GitHub here: https://github.com/EverestAPI/CelesteTAS-EverestInterop/wiki

Before submitting or uploading user files, make sure that the .tas file you're uploading contains the full movie. To do this, open Celeste Studio, and click on Tools->Integrate Read Files. This will prompt you to save a .tas file that includes all the necessary inputs, and is useful in situations where a TAS may be split up into multiple, individually edited files.

Additionally, unless your TAS is explicitly intending to use cheats, make sure you include EnforceLegal at the start of the file. This will ensure that commands enabling cheat or debug behaviour are not executed.