So after using GOG downloader and getting everything nice and downloaded, including a strange ~200-300 megabyte nameless file, all the files looked to be there. I went about verifying the cache and it told me all the files were broken (twas a valiant effort anyway), but skipping verification started installing files despite that. Some people were able to install the second game with broken files, leading to all sorts of issues, and that makes me wonder if it'd be possible with these files. Sure, the result would be a broken mess, but it might be vaguely playable or allow for some bizarre screenshots. Or maybe it'd just cancel the install at a certain point.
I'd try it myself, but I'm going to bed. Too tired to wait for an install maybe or maybe not finish.