Seems to me like you simply forgot the game was in your cart when you made the order. They don't have a phantom GOG gremlin here that adds games to people's carts as moments before they confirm the order. So it must have been your error. Considering you added the game to your cart in the first place, it must have appealed to you, even if the Interplay offer appealed more.

yep :)

Not digital download sites, no. Due to the nature of the 'product' it's impossible. You don't own the copy. Not even here.

Be happy dammit! Arx is awesome!

That certainly does sound irritating, as being able to get a refund is standard with many things. As some others have pointed out, however, with digital distribution and especially DRM-free they have reasons for not allowing refunds. In some ways you get less than a boxed version: no commercially pressed CD, no physical manual, and obviously also no refunds. It is for such reasons I am not fond of digital distribution in general. I like GOG however because while you do not get some things you would in an offline store, you also don't pay as much. Just compare that to services like Direct2Drive which also do not give you the benefits of buying off the shelf, adds more DRM with at least some games, and charges you full price for the privilege. GOG also gives extras with many games which helps to offset the disadvantages.
Heck, with EULAs what they are this isn't even much different. How many times have you purchased a game, opened the box, had the disk in the drive and ONLY THEN got a contract shoved at you to the tune of "And if you don't agree, haha sucker! Also we have the right to reject your license the next time Tom from billing's cat sneezes, or whenever we want to say it sneezed, at which time you must completely destroy the product." At least GOG is upfront with its policies.

In this thread, someone buys an awesome game by mistake then proceeds to bitch about it. News at 11!!

Fixed.

So, basically you didn't check the shopping cart and now you come here to bitch about the service. If there was a REAL problem with the site, I'm sure you'd get a different response.
And yes, it was a fair deal. Here's a list of reasons why:
1) Promotion.
2) Ridiculously low prices.
3) The only service in the world that sells old games.
4) No DRM.
5) FFS you bitch about 6$ ? And you live in the US ? LOL !
Now take your 6$, go to Electronic Arts and tell them you want to buy a non-DRM game. They'll laugh at you and tell you to go f*** yourself... and that's exactly what I recommend you do.

I'ts been said before, but... Arx Fatalis truly is a good game. I think you'll like it.

Wow. The guy is annoyed at what could very easily be taken as a flippant response (we just know better because we are part of the community) and he probably didn't think to bother checking his cart (he had six games in the cart, and had added them all in the previous two minutes probably).
So what does everyone do? They jump on his case, feel the need to constantly complain about his dissent, not to mention constantly rehashing what has already been said so that they can feel like they add their two cents.
Yeah, I am sure he wants to give GoG another shot, after this kind of treatment.

You bought one interplay game, and got one free, I don't see the issue.
buggy?
the shopping card didn't happen to look anything like this did it?
you're never buying from GOG again because of... the fact that you're blind? well that's fair, why buy games if you can't even see them. I doubt you'll enjoy Arx Fatalis as all, because the whole idea of it being a video game, means that it requires you to be able to see. Don't be so hard on the blind you guys.

Yeah, 6 games was definately too much to handle for his IQ. Not to mention the 2-minute time limit required for this operation. No wonder he didn't check the shopping cart - he wanted to avoid overloading his brain.
Now he decided to bitch about it on the forum. Nice.

Hmm, I don't quite understand that image. There seems to be some stuff missing. If you could be so kind as to completely fill out the order form and take another screen shot I would be much obliged...

POV of GOG's marketing team: "Did we lose a potential recurring customer? Should we have given him the refund? Have we...."
POV of GOG's community: "Goodbye and good riddance."