Alright guys, I don't tend to ask for opinions on forums because it tends to get ugly, but I am looking for a good single player experience to play on my PC and I would like to know what you all suggest. Here is some insight into games I like, already own and dislike. I'm currently trying out Dead Space.

Call Of Duty 4 (loved it)
Call Of Duty: WaW (didn't like the single player)
Crysis Warhead (I didn't really enjoy this one, couldn't really get into it)
Red Faction Guerilla (Playing currently on 360, love it)
Oblivion (loved it)
Fallout 3 (loved it)
Command & Conquer series (love them all)
Gears of War series (Good games)
Half Life 2 (Not bad, don't see what all of the fuss is about)
Portal (Great fun)
Far Cry 2 (Good)
Bioshock (Amazing game, loved every second)
The Settlers 6 & Expansion (Good fun)
Age Of Empires 3 (didn't like the older ones)
Mirror's Edge (Good and innovative although too short)
Left 4 Dead (Loved it)
GTA San Andreas (Brilliant)

Ok, I probably went into too much detail there, but those are some of the games I liked and disliked. I'd love to hear some of your suggestions.

Ah I forgot to add Assassins Creed and Mass Effect, loved Creed and hated Mass Effect.

I've heard tat Witcher is good, what's it about + what genre is it?

GTA IV is fun to mess around in, and liero xtreme is awesome (old tho). then umm worms series, blast is the most epic one.