Download your OS version from the Castagne website, unarchive it, and click on the godot executable. You're good to go!
Alternatively, download the dev branch version to get more features but less stability.
In order to be able to add new assets, you need to open Castagne in the Godot editor. To do that, follow this procedure:
From then on, you can now access the editor and add new assets! Press F5 to play, which will bring you to the editor.
Some progress is being made to make those steps easier as time goes on!
In order to update Castagne, just follow the procedure in the editor! Please backup your game before upgrading as a safety.
If you want to start from a blank state, these are the steps you need to take:
castagne folder at the root of the project.castagne/menus/starter/CastagneStarter.tscncastagne/Castagne.tscn to the autoload list.*.casp and *.json to the export list..castagne-local to your SCM's ignore list. (Done automatically by Castagne if you use git).This is what has been done for the Castagne generic release.
Castagne is meant for Godot 3.