I Creating a Game but in this day, Open the project say this “Unable to open project” and nothing, Please The Project Have Much Time 
When you are opening your project, does a message box pop up saying
An autosave file (backup made automatically by GDevelop) that is newer than the project file exist. Would you like to load it instead?
If this message box pops up then click on Cancel instead of OK.
and in Malformed Project en donde hago click?
Hola si tienes un .autosave del proyecto, lo mejor es hacer una copia de seguridad de todo el directorio de tu proyecto, luego borra el archivo game.json y renombra el game.autosave a game.json he intenta abrirlo otra vez.
Now there is nothing in the game.json but I did it from scratch