You have good taste, my friend...

Welcome to GOG. Regarding game suggestions, both The Witcher and STALKER are excellent games that I'd highly recommend. Risen 2 is unfortunately somewhat of a step back from Risen; you may still enjoy it, but I can't recommend it highly like the other two in your list. You may want to consider the Gothic games (Risen was basically an unofficial continuation of the Gothic games), although at the moment GOG only offers the first Gothic game (still excellent, and if you like it you can get Gothic 2 and 3 from other stores).

Other good games in the GOG catalog that are in the same genre as Fallout 3 and Risen that I'd recommend are Deus Ex and Divinity 2. Also KOTOR and Jade Empire, while a little different, are excellent games that are close enough that there's a very good chance you'd enjoy them.

If you like Risen you might try out the Two Worlds series, Divinity II: Developer's Cut and of course the original Gothic (made by the developer's of Risen). They're all modern (well Gothic is rather old) open world-ish 3D Action RPGs.

S.T.A.L.K.E.R. series is a lot different from Fallout 3, the S.T.A.L.K.E.R. games are rather hard even on lower settings, a lot less jokey and there is a bigger emphasis on actual ambiance and atmosphere. Basically Fallout 3 (to me) is a not really serious (lot's of jokes and clearly there for gags characters) Bethesda RPG, whereas the S.T.A.L.K.E.R. series is more like "Wasteland Survivor Simulator 2010". As it stands I very much prefer S.T.A.L.K.E.R. to Fallout 3 but the only thing they really have in common is being set in a post apocalyptic world (that includes mutants).

If you like the first two Fallouts you might want to try Arcanum: Of Steamworks and Magic Obscura. It was made by Troika Games, which was a developer made up of some people who had worked on the original Fallouts, and Arcanum: Of Steamworks and Magic Obscura has that same sort of style.

Oh but good taste is a curse in a way. It's tougher for us to find good games.

Call of Prypiat is pretty nice imho, it's pretty hard for me, but still it's doable. The Witcher 2 is a must play. Also since we got Disney recently, I recommend getting Knights of The Old Republic if you've never played it. It's one of the best Rpgs ever.

DarkPhoenix and NoNewTale, suggestions noted. Thanks.

NoNewTale, I liked Fallout 3 for it's mixed dynamics. It is apocalyptic and comical at the same time. It's mostly open world but also guided heavily at times by the storyline. It can be played straight through in a shallow manner, or you can dig in deeper, exploring and doing much more. I'm really not big on the shooter aspects of games, but Fallout 3 was just a fun game. I was disappointed with Skyrim, in contrast. Skyrim is huge and beautiful, but it felt pointless and repetitive, like eating a 20 lb. hamburger. I just had to step away.
Knights is in my wishlist, which I'm using to mark anything that looks interesting. Thanks for the suggestions.

If you want some open world fun, enjoy weird mixture of horror and comedy and like soft RPG (subquests, certain degree of character customization) you can take a look at Deadly Premonition. It's not that easy to make it work properly on most machines but once it's up and running it's great fun.
Those points force me to believe you'd like Deadly Premonition :) Personally prefered New Vegas btw :)

This might sound silly, but New Vegas wasn't compelling to me. I dropped out. I just didn't care about finding the guy who shot me.

Thanks for the suggestion.

I would suggest giving it one more go. The whole Ring-A-Ding quest isn't the best. But it leads you to meet Mr. House who steals the show :)

If you like RPGs, try the IE games: Baldur's Gate, Icewind Dale and Planescape: Torment. The Shadowrun games are also very highly reviewed.

Welcome to GOG, noyz! In addition to free games, Gog recently started selling DRM-free movies as well. If you want to take a break from gaming, here are a couple free movies:

http://www.gog.com/movies##sort=bestselling&price=free&page=1

I forgot, there's always The Witcher series here, they're 3D open world-ish Action RPGs, I don't like them myself (probably will give them another try in the future) but they've gained quite the following and praise.

And I somehow forgot one of my all time favorites, Mount & Blade Warband. It's not story driven, you create your own story, but it's utterly fantastic. It's completely open world, has a detailed and nuanced combat system, it even allows you to form your own armies and kingdoms. It's a 3D Action Roleplaying Game that (at times) plays out like a Grand Strategy game. There is a Demo at Taleworld's (its developer) website.

After starting this thread, Cyraxpt has gifted me Witcher 1 and 2. I'm stoked. I haven't even bought a game, yet. Who knows what Cyraxpt likes? I want to return the generosity.

White chocolate (screw the haters)
Synthwave/Dreamwave/80's style electro pop music
Dogs
Girls (i want Audrey Hepburn clone)
Etc

On a serious note i actually prefer not receive anything in return, feel free to do an open giveaway if you want to repay the generosity, other than that, a thank you and playing the games will suffice.