Games that are nearly always on my system?
X3 Reunion
Space Rangers 2 Reboot
Ultima 1-9 + U1,U2
Quest for Glory 1-5
ArmA
Falcon 4 Allied Force
Enemy Engaged Apache Havoc & Comanche Hokum + mods
Tiger Woods PGA Tour 08
Diablo 2
Sim City 4 + Addon
Supreme Commander & addon
Open Transport Tycoon Deluxe
Shogun Total War
Evil Genius
Dungeon Keeper 2
TES Oblivion
Hitman 1-4
Fable
Need for Speed Underground 2 and NFS 4
Sid Meier's Pirates
Silent Hunter 3
Sniper Elite (best sniping game ever)
Swat 4 + addon
Steel Panthers WW2&MBT
Pirates of the Caribbean
Stalker Shadow of Chernobyl
Thief 1-3 (3 is personally my favorite, mainly because it cut back on the nonsense with arrows and alerted guards of the other 2)
They arn't all on my computer at once, but cycle and and off frequently. Also doesnt include most of my old dos games, or all the console games I use to own.