I prefer RPGs, some strategy, and some action adventure. Maybe even a shooter, as the last game I got was Duke3d with the Hi-Res Mod. From GOG I already own:

Fallout 1 & 2
Baldur's Gate 1& 2
Icewind Dale 1 & 2
Age of Wonders
Seven Kingdoms
Sacred Gold
Arx Fatalis
Advent Rising
Two Worlds
Gothic 2
Septerra Core
Never Winter Nights

I hear good things about Arcanum, and that's a possibility, but one game that has caught my attention is Outcast. It has an interesting look and the reviews make it sound interesting. Good Sci-Fi is hard to find. What are your favorite games in the genre? Any suggestions for my next favorite game?

Buy Blood 1 and 2 they are freaking nice! Good FPS games. :)

Not a fan of adventure? Those are the older games I can usually recommend most.

Dragonsphere is free, so I'd suggest starting there. I haven't actually played it myself, but I don't feel comfortable recommending individual titles until you know your opinion of the genre in general.

Alright, I'll give that one a try. I'd started playing Beneath a Steel Sky, but couldn't really get into it. I wasn't sure how good a representative of adventure games it really is. I've looked at shots of Syberia and think it looks interesting, same with Dreamfall.

You ought to try Sacrifice.

I didn't like Syberia when I tried playing it years ago. Dreamfall I recall being a fairly decent entry point. And it's the reason I got The Longest Journey (Dreamfall is the sequel, they stand on their own well enough), but I'd consider The Longest Journey harder to get into.

Also, Telltale Games occasionally has a free Sam and Max episode.

If you liked Age of Wonders, get Master of Magic.

BASS is a fantastic adventure game, and a very good representative of the genre. Some of the puzzles are a tad on the difficult side though.

If you want to get into adventure games, and want something that's not too difficult, you should try to get your hands on a copy of Loom. It very different from anything else, but it's not very difficult, and has a fantastic story. Finding a copy (legally) might be very difficult though.

Search subroutines enabled.
Result found.
http://store.steampowered.com/app/32340/

Sacrifice
Age of Wonders
Arcanum

Ah, I wasn't aware that it was on Steam. I never buy anything there. Well, there you go. If you don't mind buying games on Steam, get this. Like, right now.

For (a bit action oriented) RPGs, Might & Magic VII or VTM: Redemption are also good choices.
But I also second Loom, it's a great little gem ;)

Additional: I like the fact that they have the original advertisement blurbs on the page. Now, I love the art style of the game, and the graphics are very beautiful, but there are no "Stunning, high-resolution, 3D landscapes" in there :-D