If we are to believe pedrovay2003's guide, then neither of the previous Witcher games had CEG. Of course, not having CEG doesn't mean that you can just run it without the client (for instance, Angry Video Game Nerd Adventures doesn't seem to have CEG, but it will still refuse to run without the client).

Some Steam games that don't have CEG but still won't run without the client, can simply be turned DRM-Free using a steam_api.dll file from a known DRM-Free game such as Rise of the Triad (remake).

As far as I know it's entirely up to the developer/publisher of a game if they use any form of DRM on Steam. So they can decide whether they want to use 3rd party DRM (like SecuROM PA, Solidshield or Tages), Steam stub or no DRM at all.

What I'm wondering is the following: does it cost money to use Steam's own copy protection or is it free of charge? Because then it would make sense that remarkably lots of indie developers seem to use no DRM whatsoever to keep the costs as low as possible, whereas AAA studios with big budgets can afford to use as much DRM as possible to prevent pirating.

The things said before are exactly right: CEG is a completely optional, second-level DRM that Valve offers to Steam developers/publishers, and its implementation is 100% up to the developers/publishers themselves. The standard client requirement DRM is also optional, as it's been made obvious by the list of DRM-free Steam games on the wiki that we keep updated in this very thread.

Both Witcher games (and AVGN Adventures, as mentioned above) do in fact require Steam to run, but neither one has CEG, meaning that they can be copied/pasted with an offline Steam client as outlined in my guide. If you were to take a CEG game and try it, like Spec Ops: The Line, the game might launch offline, but it will crash until you go online and re-download machine-specific files. Luckily, CEG is barely used at all, and even Valve itself has patched CEG out of some of its games, like Portal 2. As far as I can tell, Linux doesn't use CEG at all in any games.

I actually find that quote from CDPR interesting, because they DO have complete control on Steam. Hell, not only with CEG, but they can choose to not even require the basic client DRM if they don't want to, and I'm kind of surprised they haven't done that so far. At least the Steam versions can be redeemed on GOG.com for DRM-free versions.

Thank you (and the others) for the useful insights, added the client requirement in the post I linked above, and now at least I know I wasn't completely in the wrong on it being optional.

No problem at all! I honestly love this stuff.

The easiest way to check for CEG is to go to https://steamdb.info/ and search for a game. Go to the Configuration tab, and if it mentions anything about a cegpublickey or checkguid, then it has DRM. Here are a couple of examples:

AVGN Adventures (no CEG):
https://steamdb.info/app/237740/config/

Spec Ops: The Line (CEG):
https://steamdb.info/app/50300/config/

Since it seems to take forever with the "real" DRM-free release of Dreadout. Soes anybody know it the Steam version does run without Steam being active?

Unfortunately, DreadOut is not DRM-free; I even tested the Linux version. I'm waiting for the DRM-free version, too, but I'm starting to wonder if it's actually going to happen at this point.

Yeah, I remember them promising a DRM-free version to backers, too. I think that will still happen, but I'm getting worried about a public release.

I may have something to add: Red Faction

When you download it, in its steamapps folder two subfolders can be found: RF_1 and RF_2. These two folders contain the installer of the two discs of the original retail version. Just run setup.exe from RF_1 and point the installer to RF_2 when asked for disc 2 (you can also copy all files in one single folder making the latter unnecessary).

After installation download and install the Pure Faction mod. This fixes also some problems on Windows 7.

Holy crap, that really works? The game runs without Steam if you install it separately from the RF_1 folder? That's amazing if true.

Also, is the Pure Faction mod required for it to run without Steam, or will it run without the mod and just not play as well?

Yeah that works quite well. Doesn't pure faction run without Steam even if you are running the Steam copy?

I have no idea, I don't have the game. I'm honestly tempted to get it for $5 on the Humble Store just to test this, though.

Bah, even with running Steam it is worth it. Absolute classic.