So I finally bought a couple DRM free games on GG during the sale and it all works well if you backup your files during install, as talked about elsewhere on these forums.
I notice GG has a LOT of games not available anywhere else that are from Eastern Europe and other countries. Few of them are hyped at all or even rated, but I know there may be some gems in there.
Anyone want to suggest some good games I could get? I care mostly about classic gameplay and immersion in unique worlds.

I personally loved Gods : lands of infinity. Very unique game that combines western rpg with some jrpg elements (such as turn-based battle for example). There is also possibility for the player to speculate on a free market in order to make decent profits. Nothing really deep though. The scenario is boring and surprising at the same time. The game is rather superficial but terribly charming (and I am not only referring to the heroine). The musics are amazing and the overall atmosphere so unique that I'm asking for more. Even if I'm afraid that the sequel won't come out... /cry.
Unfortunately the game is unfinished and some features seem to be missing. But nothing that prevents you from finishing the game. The game is so peculiar that I would suggest you to try out the demo.

I don't know if you can classify it as Eastern Europe, but Spellcross is an awesome strategy game where a magical army (orcs, mages etc) invade modern day Earth and you have to fight back with modern units.

The Witcher! :p

If you are in tactical turn based games then you can give a try to Flottila. I think it's not from Eastern Europe but a good game.

Faces of War - is real time strategy, combination of Company of Heroes and Jagged Alliance with great attention to details.
http://www.youtube.com/watch?v=zYC45WcIVjU
And also Emberwind - not from Eastern Europe, but good classic platformer (now 66% off)

There's Pathology and The Void which have offers from time to time.

You didn't mention which ones you bought.
The Stalker games stand tall as not only my favourite Eastern Europe games, but also as some of my favourite games full stop. Pripyat and Chernobyl are the best as just about everyone else will confirm.
Seconding The Void. Pathologic is due either a remake or at least a re-translation depending on what the devs decide. Looks like they're going for the translation right now.
King Arthur's Roleplaying Wargame is an impressive blend of Total War style gameplay with various roleplaying aspects thrown in, such as loot, magical powers, choose your own adventure style sections and, of course, levelling up. Lionheart's due out soon too.
The Witcher, obviously. Very well told story and combat that's far better than most in the genre.
Edit: Oh and Men of War. Another fantastic game in its own right.
Dammit I also forgot Cryostasis. Amazing game!
Then there's Necrovision too which is somewhat like Painkiller, but it really comes into its own about halfway through.

The Void and Gods seem to be good suggestions, thanks guys. I bought a couple of $2 games just to test the system, one was Vivisection and one was Planet Alcatraz, they both seem pretty terrible.
I already own all the STALKER games, Necrovision and Cryostasis... those are generally more well known.

I'll keep that one in mind, it looks interesting to me.
Edit : I meant to ask : where did you buy the game ? I did check GamersGate but the game is at 19 dollars...

They just changed the sales today, sadly. It seems like a Fallout clone almost to the letter.