Grand Theft Auto (10/10)
San Andreas
GTA V
GTA IV
Legend of Zelda (9.8)
Twilight Princess
Majora's Mask
Ocarina of Time
Fallout (9.6)
Fallout New Vegas
Fallout 3
Fallout Brotherhood of Steel - haven't played 1 or 2 =(
There are other series that I love, but these are my top 3.