If we're talking about DRM as in a measure to prevent copying, or require online security check, or anything like that, then no GOG game has DRM. One of GOG's core policies is that all of their games are DRM free. However, some people have stretched the definition a little to include other stuff. For example, if an online multiplayer game requires GOG Galaxy to connect to its online servers, some people consider that to be DRM.

There are some posts on GOG's official forums where people try to list all the games that have "DRM" of any kind. So if you're interested, that's where you could look. But if you just want to have confidence that you'll be able to install and run the game in the future, then don't worry about it. No GOG game has anything that would prevent that.

[–] Aceticon@lemmy.world 14 points 1 day ago

The info is here and none of that "DRM" means you can't in the future, after the servers are down, install the game from your copy of the offline installer and play it.

None of that is DRM in the sense we're talking about here: the kind of mechanism that allows the game to be taken away from you or won't let you install it or play it in single-player anymore when the publisher decides they don't want to pay for servers anymore.

It is, none the less, a deviation from the No-DRM promise, IMHO.