The Codex has made me into a paranoid asshole so that now I see all these threads as a troll attempt.
I will try to rid my heart of this degeneracy now by responding to the OP. Lord have mercy on me.
Firstly, the codex top games are worth playing.
Second, I'll list the games that I think are REALLY worth playing and have played myself
my favourites are (in the order I'm remembering them):
Operation Flashpoint,
Mafia,
Hidden and Dangerous 2,
all the Hitmans except for the last one which is shit.
Age of Empires 2-3. Red Alert 2.
C&C Generals,
Tiberiums Wars. Warcraft 3.
Lineage 2 C4-5 only
Commandos 2
Day of Defeat
Counter-Strike
Jedi Knight 2 + Jedi Academy
Thief 2
Quake 3
Unreal Tournament
Syberia
Divinity 1, 2 and OS
Diablo 1+2
Disciples 2
Homam 3 + 4
League of Legends
Cossacks
Broken Sword (only 1)
Splinter Cell: Chaos Theory
Blade of Darkness
GTA 3+VC+SA
That's all I can remember now. If you like their genres you can't go wrong with any of them, imo.
I don't know which ones are PC exclusive but they are all better played on PC unless you're a retard who can't aim with a mouse. If you come back and actually care about it, I'll write stuff for each game what makes it good etc.