First glance I'm missing:

Uplink: Hacker Elite
Betrayal at Krondor Pack

Likely because I missed it in a sale or promo. One day...

The top one I don't own on GOG: Planescape Torment. I have it on CD.

The top one I don't own at all: Neverwinter Nights 2. I'll probably be getting it on CD as well so I have the full collection.

The top one I'm not interested at all in buying: The Witcher.

Theme Hospital.

EDIT: See this post? Something like this happens when you don't read. Or can't read. Or, basically, when you are stupid like me! XD

Sacrifice! :P

Jokes aside (well, even Sacrifice can qualify, actually) I don't own many famous games, even real "essentials" like Quake.

The most famous GOG game I'm missing is probably "The Secret of Monkey Island", and I definitley need to rectify this.

Among the absolute best-selling non-GOG games I don't own, the top position is probably occupied by Skyrim, but since I have not even the slightest interest in it I guess it's fine.
Plenty of AAA games I don't own. Basically all of those released after 2010! :P

Me too.

Star Wars: Tie Fighter


I'm waiting for a decent discount before I purchase any of the LucasArts games. I've been tempted greatly, but I've triumphed over temptation so far.

Arcanum on place 15.

I don't own Dungeon Keeper 2 in any format (and too much backlog to buy it in the foreseeable future).

Skyrim
Diablo 3
Call of Duty
Dragon Age series
Mass Effect series

And i don't plan on ever getting them. The only one of those i would seriously consider, is Skyrim. But i won't. Compared to Morrowind it is a dreadful bugfest lacking on so many mandatory gameplay features that Morrowind had.

Same here. The first three games are part of the D&D bundle that I bought on a winter sale so they were hard to miss.
You wouldn't even get it to play Skywind? :-)

I don't own Dragonshard either. Tried it back in the day and got too bored to finish it.

Nope! For me, Morrowind is best. And i like its old style graphics. Plus they are awesome for my old system and all.

Well, that's a matter of taste. I have a lot of questions I'd like to ask Bethesda about "brilliant" decisions they made in Skyrim (No spellpower scaling? Just one ring slot? Lots of spells removed? WTF guys??!) but I have to admit I like its gameplay mechanics better than that of previous games.
I'm not big on graphics but the (unmodded) faces of Morro are just plain scary; also its crafting possibilities are somewhat limited, there are barely any means to speed up your movement (aka horses; well, there are certain boots of course but it takes time to find them). So if there happened to be a game with Morro's spells, story and atmosphere and Skyrim's crafting system and gameplay mechanics - it'd be an instadownload (since the mod's gonna be free) for me.

Master of Orion 1+2

For me this is more of which ones I DO own. Looking at the first two pages of the bestsellers, I have six of them. Of those six, the only two of them I have played are the Witcher and Descent 1/2.