Watching "bestsellers" column changes, I try to find - are these games real bestsellers, and it changes in real time reflecting the real sales online, or is it just a promotional trick?

There's different Bestsellers lists. Some show a running average of perhaps a few days/week(s), the other is the all-time best-selling. And as the site is updated, which best-selling list keeps changing.

Right now, the all-time-best-sellers-list is here: http://www.gog.com/games##sort=bestselling&page=1

Well, I asked mainly about the main page bestsellers. I just noticed some minutes ago that the set of games there has been changed, Wasteland 2 disappeared and Heroes 3 appeared...:)

Umm, Wasteland 2 hasn't disappeared; it's still first (and the Digital Deluxe Edition eighth). As far as I know, the main page best-sellers are the current best-sellers.

good to see the neverwinter nights series in that list :D

Yes, now it's like that and like it is used to be for last two weeks. But I swear that Heroes 3 were there sometime ago. Maybe a bug.
And current for what period of time?

The GOG bestsellers are real.

The GOG forum is surreal.

Heroes 3 is still there (9th position). It likely tracks daily sales, as Ascendant (which had a promo that ended 7 hours earlier) can still be seen on the best-sellers list.

I was recently thinking about that bestsellers list and here are my conclusions (please correct me if I'm wrong):

- the list is based not on quantity of games sold, but on value of the sale. For example one sold copy of Witcher 3 will be 'worth' more on the list than 4 sold copies of Star Wars: X-Wing,
- the list contains sales from last 72 hours and it's (+/-) real-time based (refreshed every half an hour or every hour rather than refreshed once a day).

Am I correct? And I'm speaking of 'bestsellers' list located on the main page, not all-time bestsellers list.

How Can Bestsellers Be Real If Our Games Aren't Real

Tie Fighter is on page 9/17.
X-wing is on page 10/17.
SS2 hold your pants !

That's roughly half the list beaten in less than 8 hours.

It's just calculated differently. The main list is 'of all time'. If the front page was like that then new games would never, ever feature. So it's based on a smaller amount of time, It used to be based on the last couple of days.. But now it might be a matter of hours.

Well it's PS:T that is firmly settled in #1.
Are you real?

Looking at the bestseller list, wasn't Crawl already released?
http://www.gog.com/game/crawl
Or do I remember that wrong?

Wrong. It's still on early access.