I’ve written up a python script for downloading all your projects, with asset downloading (but not source code rewriting) over on https://gist.github.com/Pomax/19244d583bac820492847a8a4bc15e4e, you can either invoke it directly, in which case it’ll ask you for your glitch user id and persistent token (both can be found in your browser’s localStorage.cachedUser for glitch.com, the script will tell you how to look them up when you run it) or it can be called as python3 download.py youruserid yourusertoken and then it’ll just start running without asking you to type anything.
This should work on both Windows and *n*x but you kind of want tar to be available (always true on *n*x flavours, including MacOS, but not necessarily on Windows). If you don’t, then all this script does is download your project archives, without any sort of unpacking or automatic asset downloading.
It’s probably not perfect, but it should get most of the job done, so if you run into any problems with it let me know either here or as gist comment and I can try to get things fixed up when I have time (or if you know the fix, drop some code in a gist comment =)