That's because there is no download. You're expected to clone the repo using git. But I'll see if I can fix that or something, thanks for the heads up.
Strange... the only thing I changed was to add an Issues tab[1]. I'm not sure why it worked before (I never tried to download the repo, only clone it), or why it broke. I agree that downloading a zipped file can be easier than cloning a repo (not by much, though). In that case, I may need to start a new GitHub repo, where the master branch is Arc/Nu (or whatever I want to call it). That would also be the time to do the rename.
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* [1]: Yes, akkartik, it is possible, I figured it out not too long ago. :P