Had I not recently performed a clean install of Windows 7, I would have checked the 20+ (although many were ancient games). Now, I only have 1 - 5 checked because I haven't had time to get all that I want installed.
20+ have some older ones i have installed on an old athlon
Command & Conquer First Decade (6 games)
C&C Red Alert 3
C&C 3 tiberium wars
C&C 3 Kane's Wrath
Left 4 Dead
Day of Defeat
Half Life
HL Opposing Force
HL Blue shift
HL2
HL2 Episode 1
HL2 Episode 2
Portal
Team Fotress 2
Unreal Tournament 3
UT 2004
Dawn of War 2
Dawn of War
Dawn of War winter assault
Dawn of War Dark crusade
Dawn of War Soulstorm
Return to Castle Wolfenstein
RTCW: enemy territory
Wolfenstein
Wolfenstein 3d
Company of heroes
COH: Opposing Fronts
COH: Tales of Valor
Civilization IV complete
Operation Flashpoint complete
Operation Flashpoint Dragon Rising
Fallout 3 GOTY
Crysis
Crysis Warhead
Witcher Enhanced Edition
Grid
DragonAge: Origins
Far Cry
Far Cry 2
Stalker SoC
Battlefield 2142
Battlefield 2
Battlefield 1942 collection
Hellgate London
Oblivion GOTY
Neverwinter Nights 2
NWN 2: Mask of the betrayer
Brothers in Arms: road to 30 hill
BIA: Earned in blood
BIA: Hell's Highway
Need for speed Shift
GTR: evolution
GTR
GTR 2
Race 07
Quake 4
Quake 2
Quake live
Doom 3
Doom 3 Resurrection of Evil
Ultimate Doom
Doom 2
Final Doom
Borderlands