Rather than doing things the hard way, why not just try using NTFS compression
on the games in question?
What if I'm not using NTFS? (On Linux, NTFS isn't used much, and I wouldn't trust the driver to handle advanced features properly or even at all.)
As my response was addressed to a Windows user, it will clearly have little relevance for those on other OSes. If you use Linux, then the ZFS and BTRFS filesystems offer similar facilities.
You don't realize how outrageously expensive that is? That backblaze article ends with "we think the world needs lower egress fees" and I fully agree...At 0.085/GB, a game that takes a few tens of gigabytes would cost a few dollars to transfer. Now take a game like Wolfenstein: The New Order and assume GOG's cut from the 20 eur asking price is the industry standard 30% or 6 eur. That's already in the "few dollars" range, and I believe that price includes VAT. That's bad even before any kind of discount...
At 44GB, Wolfenstein New Order is currently at the top end in terms of download size - most of the games on GOG are less than 5GB (and many under 1GB). That $0.085/GB for AWS is a starting
rate which slides down to $0.03/GB - plus there are cheaper providers
(as low as $5,000/PB or $0.005/GB) available.
It seems like this drama suddenly ends with Unity's damage control..."We have heard you...Thank you for your honest and critical feedback".
Translation: "Please stop sending mailbombs, dog poop and SWAT teams to our address. We will devise another form of wording that sounds nicer and cuddlier but essentially does the same thing. This will be publicised once we have vested and sold all our remaining stock options. What a bunch of tossers you are."