Hello, I’ve just finished my first game, a 2d platformer.
However, I want to publish it on Itch, and for that I need to download it.
How do I download it as a .json file?
If you exported your game and deleted the project, you don’t download it. It can’t go backwards from export to project.
If you just mean you have a cloud project, just export (share button) and choose the browser option. Then just choose the HTML5 export. You’ll need to upload the entire zip file it creates to Itch or similar services.
It is explained here : Publish to Itch.io - GDevelop documentation
But I think that you want to say “Upload” and not “Download”, no ?