Why there are bunch of unavaiable games in free category with tag "soon"? Some of these games have this tag for months. So whats reason for this? This tag should be only for games which will be avaiable for free in month.

Just bugs. Once those games get released, they will be removed from the FREE section.

An educated guess would be that the code searching for "free" games is faulty, and returns all games in the catalog that do not yet have a price attached. The faulty logic assumes that "no price" = "free", which is of course wrong.

^This
The game's aren't free, they just don't have a price yet. The filter is wrongly interpreting this as them being free.
Once they are released (or even awhile before that if they get a price in advance as some games seem to) they will no longer appear there.

Some games who are labelled TBA or "to be announced".. are not on the sales yet that's why it's free because it doesn't have a price... It doesn't mean it will be free if it's released..

So, all games which are in development are in free category? Also, it isn't so soon when game is sitting in this category almost year.

No no, it's not "soon", it's Soon™.

No, so it is a bug.

BUG! confirmed!? :P

You mean like Crawl, which apparantly was announced at the GOG party in August 2014 as "coming soon"? ;)

Crawl is a reverse freebie.

GoG is going to charge US to remove it from the Upcoming list. Once they reach U.S. $32,000 (a figure I understand "Allows for us to throw a kick ass party") they'll finally take that corpse down from the castle wall.