Heres the 15 best:

Metal Gear Solid (1998, PlayStation, PC)
Grim Fandango (1998, PC)
The Longest Journey (2000, PC)
Grand Theft Auto: San Andreas (PS2, Xbox, PC, 2004)
Beyond Good & Evil (PS2, Xbox, GameCube, PC, 2003)
Astro Boy: Omega Factor (Game Boy Advance, 2004)
Portal (Xbox 360, PC, PS3, 2007)
Gabriel Knight: Sins of the Fathers (PC, 1993)
Bioshock (Xbox 360, 2007)
Planescape: Torment (PC, 1999)
Fallout 2 (PC, 1998)
God of War (PS2, 2005)
Star Wars: Knights of the Old Republic (Xbox, PC, 2003)
Final Fantasy VI (Super Nintendo, 1994)
Silent Hill 2 (Xbox, PS2, PC, 2001)

Check The Rest HERE