As of 2011:
Sonic the Hedgehog
Sonic the Hedgehog 2
Sonic the Hedgehog CD
Sonic Spinball
Sonic the Hedgehog 3
Sonic & Knuckles
Sonic Labyrinth
Sonic 3D Blast (Flickie's Island)
Sonic R
Sonic Adventure
Sonic Pocket Adventure
Sonic Shuffle
Sonic Adventure 2
Sonic Advance
Sonic Advance 2
Sonic Battle
Sonic Heroes
Sonic Advance 3
Shadow the Hedgehog
Sonic Rush
Sonic Riders
Sonic the Hedgehog (2006)
Sonic and the Secret Rings
Sonic Riders Zero Gravity
Sonic Chronicles: The Dark Brotherhood
Sonic Unleashed
Sonic and the Black Knight
Sonic the Hedgehog 4: Episode 1
Sonic Free Riders
Sonic Colours
Sonic Generations