This is a soon-to-be complete set of soundtrack lists from the Sonic games, including unused/beta tracks. I would like to add, for fun, a list of remixes in the future. A huge thanks goes to WB for sharing his huge music collection with me! :D

Old School

Sonic the Hedgehog 1 (Genesis)
Sonic the Hedgehog 2 (Genesis)
Sonic the Hedgehog 1 (Game Gear)
Sonic the Hedgehog 2 (Game Gear)
Sonic Spinball (Genesis + Game Gear)
Sonic Chaos (Sonic & Tails)
Sonic CD
Sonic Boom
Sonic 3 & Knuckles
Sonic 3 & Knuckles Remix
Sonic Drift
Sonic Triple Trouble (Sonic & Tails 2)
Knuckles Chaotix
Sonic Drift 2
Tails Skypatrol
Tails' Adventure
Sonic Labyrinth
Sonic 3D Blast
Sonic Championship (Sonic the Fighters)
Sonic Jam
Sonic R
Sonic Blast
Virtual Sonic
Sonic Team Power Play

New School

Sonic Adventure
Sonic Adventure: Songs With Attitude Vocal Mini-Album
Sonic Adventure Vocal Remix
Sonic Pocket Adventure
Sonic Shuffle
Sonic Adventure 2
Sonic 10th Anniversary Special
Sonic Adventure 2: Cuts Unleashed (Vocal)
Sonic Adventure 2: Battle
Sonic Mega Collection
Sonic Advance 1
Sonic Advance 2
Sonic Advance 3
Sonic Pinball Party
Sonic Heroes
Sonic Heroes: Triple Threat (Vocal Trax)
Sonic Battle