It seems downloading this large game is problematic for quite a few users.
Perhaps offering a Torrent link for download has been already considered and rejected? It would help if net keeps disconnecting, I believe it can continue from where download was interrupted. It would also scale when new version is publised and umpteen thousand gamers download at the same time.
One hack I invented myself would be splitting game to smaller pieces. The big pieces of the game are the .rpa files in game-directory. Offering them as separate .zip files would mitigate the problem of one huge > 13GB file and interrupt during transfer. The largest .rpa is v09.rpa, 3.2 GB. Putting the > 0.9 GB files each to its own zip and collectin the smaller .rpa files to about 1 GB files would make about 10 .zip files, and then the rest of the game the 11th. So user would need to do 11 separate downloads and unzip them manually. Maybe this could be tried and see if it helps gamers with slow of flaky connection.
There is also Itch app, which no longer can download HH since version 0.19, when game is only on third party websites and not on Itch.io. This is a hurdle for those accustomed to the easy game install and update using the app. I do not know what to do about this except upload game also to itch.io.