I keep two backup copies of everything on a couple of 4TBs. Extras, old and current installers for mac & windows.

Several years ago, when they were moving out of beta, they apparently had to go offline for a few days for some reason. Instead of telling everyone, they thought it would be funny to let everyone think they went out of business. Some people never got over it.

At the very least it was a wake-up call.

Indeed. If it got people to finally backup their shit, I'd say that's a nice, shiny silver-lining.

Yeah, I have a full backup of both Windows and Linux installers (where applicable) on an external hard drive...

... and on a different external hard drive I have a backup of that backup. I call it do-it-yourself-RAID-1.

I prefer DVD's for data storage but I'm now considering an HDD because I can easily update my games without having to burn a completely new disc and consume a lot of space in my desk. I'm paranoid with drives though, so I'll still end up making a 2nd copy on a secondary one.

I've got an external hard drive or two for the sole purpose of backing up all my digital games and music, along with the gaming soundtracks I have and all the game mods/unofficial patches.

This is the downside. I feel like every time I get around to burning things, the full installer updates all over again! What was that? Starpoint Gemini 2 updated last night without a flag? Dammit!

For some of my GOG games I have a Steam backup. ;)

I have some of the games backed up on a DVD or Blu-ray, but most of them are not backed.

What do write cycles have to do with anything? Backup devices are pretty much a one time write.

For me the answer is yes, as well. I always back up the games to an external hard drive as soon as they are added to my account and I finish the download.

What would be the point of DRM-free installers, otherwise? :)

Yes, on an external backup-drive on my desk and a second backup on an external drive stored elsewhere. Both I only connect for backup purposes.

The GAMES folders there contain all setups for all games however, not just the GOG ones, with the exception of games that can't be backupped due to DRM (I'm looking at you Origin and UPlay).

I've made regular internal and external backups of pictures, home movies, and personal files like Quicken and TurboTax for years. The picture and home movie files are already over 400 GB. So adding GOG download backups to the list has been easy to implement.

One backup is to one of three internal 3TB hard drives. Then every couple of months I make a backup to an external hard drive and rotate it with the backup hard drives stored in safe deposit boxes at two banks that are located far apart.

Really important files also get backed up more frequently to Blu-ray discs, DVDs, and/or USB flash drives. In the future I will be making these backups to M-Disc Blu-ray discs which should last much longer than regular Blu-ray discs.

With EMPs being in the news lately I may start wrapping the external hard drives in layers of aluminum foil and insulator before storing them at home or in safe deposit boxes.

I realize this may be a paranoid reaction, and for game backups it probably is. But if I'm using these techniques to save one-of-a-kind photos, home movies, and personal files, I might as well add in GOG games.

P.S. This paranoia stems from my grandparents losing all of their one-of-a-kind family photos and personal records in a house fire about 50 years ago, and my sister having a similar loss when her house burned down about 15 years ago. Living in the center of tornado alley doesn't help with this issue!

I've thought about it. But with so many new releases coming in regularly, both old and new games, it's unlikely that I'll even have the time to replay a game. A few of them are worth it, though.

I have, and I'm starting to run out of space on my home server/firewall/vpn/NAT/whatever-I-feel-like-tinkering-with-computer because of it. It's taking more than 1/4 of the total space available. I have kept it current until recently with lgogdownloader (windows installers+extras, would have run out off space long time ago if I also kept linux installers), but I have grown a bit lazy with Galaxy becoming usable. Right now it's 580.6GiB, and it's already missing few recent acquisitions - like Morrowind or the Van Helsing trilogy to name the more heavy ones.

Need to buy bigger disks eventually, but I'm still putting it off. If I have to deal with moving the data, I want to do it properly this time, to last for a while. Right now I only have RAID-1 "backups", and no integrity guarantees besides what is provided by the installers themselves. Since there is still some space left, I'm hoping I would be able to delay it until btrfs is mature enough to use it both as primary storage and to do external backups with btrfs send utility.

No, and I don't see any reason to have one. If someday GOG does disappear, it's not like all of their stuff isn't already "backed up" on certain other sites anyway.

EDIT:

I don't know why you're so certain about that. Plenty of companies have been around for over 100 years and are still going strong.