I like classy games. My personal best off:
Cod Uo
Jagged Alliance 2
Age of Empires 2
Half-Life 1
Unreal 1
Unreal-Tournament 1
Half-Life Opposing Force
INCOMING
Day of the tentacle
Deus Ex 1
Funk Flitzer
Bleifuss
Bleifuss Fun
Couple of old StarWars Games like X-Wing Vs. Tie-Fighter
Knights of the Old Republic
Re-Volt
Collin McRae Ralley
C&C 1, 2, Generals
Battlefield 1942
Battlefield Vietnam
Counterstrike
GTA 1, 2, Vice City
Serious Sam
Worms
Warcraft 2
Trackmania
Mathblaster (OK, that is for children, but I was one...)
Descent (who remembers this?
http://atkdmg.com/wp-content/uploads/2011/04/descent.jpg =)
Doom 1-3
Quake 1-3
Portals
Battlefront 1 & 2
Rayman (also game for kids)
Old Indiana Jones Games!!
And some others.