good game, question when you download do you still have the world that you made in browser?
Short answer: no
Long answer: If you press Ctrl + Shift + I and go to the Application tab, then expand IndexedDB, then expand /idbfs - https://v6p9d9t4.ssl.hwcdn.net/ and then click FILE_DATA you can see your world's save file, but I have no idea how to download it.