The key isn't DRM, actually. It's used by the games to differentiate between two different clients. It's how the game knows who's giving what commands via network. While it's possible to architect a game in a different fashion than this (and, indeed, many older games do use a different system for it), it is how the games that require serial keys work, and short of getting access to the source code and rewriting the entire way the multiplayer code functions, there's no addressing this.

As for why we don't give you more than one key, well, technically you shouldn't be playing co-op with a friend if you only have one license for the game anyway. Of course, we don't use DRM so we can't exactly enforce this, but the general analogy we use is "treat your download like a CD". If you loaned the CD to your friend to play, you wouldn't be able to play it until he gave it back. Treating GOG.com downloads the same way seems fair to us, so that you can still share your games with your friends--but only if you're not using them while you do.

EDIT: NInja'ed by Sir PrimalForm. :: shakes fist ::

In our T&C, you are correct. But if you ever read any of the EULA's for any game you download ever, you'll see you're actually purchasing a single-use license. If you install the game on eleven computers that you own, that's fine, as long as you're the one playing it. After all, a game installed on eleven computers doesn't matter, since you can only physically play one computer at a time.

Okay, it's probably possible to play more than one computer at once, but it's hardly practical.

I'm apparently not smart enough, then, since I would undoubtedly fark up trying to plan strategy in a MOO and HOMM game simultaneously. ;)

I'm not convinced we have ever had that as a slogan. We do say, "DRM-Free. Fair Prices. Customer Love." Our last slogan was, i guess, "DRM-Free Classic Games." Before that, I'm not even sure we had a slogan.

Do we tell you that you are free to use your game unhindered by DRM? Well, yes. But we don't say you're free to use your game unhindered by any EULA anywhere. These are specific legal contracts.

Yes, some games allow you to install them multiple times and play them via LAN; those very same games don't require a CD key to play online and--presumably--have a different EULA.

Some games don't. Their EULA tells you that you're buying a single-use license. As such, only a single person is allowed to be using it at a given time.

On to the root of your question, though: I would argue this kind of CD check for online play is not DRM. It's more like a philosophy of multiplayer design. Some programs are built to allow you to communicate with other players. Some aren't.

Arguing that JA2 has DRM because it's not designed to let you play it in the manner you want to because there's no online mode is incorrect. Likewise, I think that saying that a game has DRM because it doesn't have "everyone in my LAN can play off of my one CD" is fallacious; the designers elected to make the game a certain way. Either you play along or you go and buy another game.

Now, you may argue that any CD check at all is DRM. That's a harder argument to defend against, simply because there are very differing opinions on what DRM is. Suffice to say, GOG.com does not agree with you in this regard, given how very anti-DRM we are.

Oh, hey. I didn't write that, thus why I don't recall it. :P
No, you misunderstand: he gets one license. If he's the only one using the game, he's free to install it on any PC. He doesn't have to own the PC he's installing the game on, he just has to be the only person who will be playing it. If he installs it on your PC and then deletes it when he's gone it's all kosher.

Or he could leave it on, really. If you own your own license of the game, you're probably gonna be playing your own install. :P

I'm sorry to hear that you're having problems with recruiting a friend to play Two Worlds. Let's just say that GOG.com doesn't agree with you that CD Key checks are DRM and leave it at that while we try to solve your problem.

if you're willing to buy another copy of the game for this trial for your friend, this is easy enough to solve. Gift a copy of the game to some email address-any address you control will do. Make a new account with that address. Contact support and ask for a key for it. Get key. That should solve it.

As for why we don't post this kind of thing everywhere? Because, frankly, no one's ever asked for such a thing in four years of business. I think you're enough of an edge case that it's not the kind of thing that we'd anticipated.