Megadrive

Sonic The Hedgehog

Sonic The Hedgehog 2

Sonic The Hedgehog 3

Sonic & Knuckles

Sonic Spinball

Sonic 3D: Flickies Island
Mean Bean Machine

Sonic The Hedgehog CD

Knuckles Chaotix
Sonic Compilation
Game Gear
Sonic The Hedgehog
Sonic The Hedgehog 2
Sonic Chaos
Sonic Spinball
Sonic Triple Trouble
Mean Bean Machine
Sonic Labyrinth
Sonic Blast
Sonic Drift
Sonic Drift 2
Tails' Adventure
Tails' Skypatrol
 
Sega Saturn
NiGHTS Into Dreams...
Burning Rangers
Sonic R
Sonic Jam
Sonic 3D: Flickies Island
Christmas NiGHTS
 
Dreamcast
Sonic Adventure
Sonic Adventure 2
Sonic Shuffle
Phantasy Star online/V2
Chu Chu Rocket
Samba De Amigo
 
Gamecube
Sonic Adventure 2: Battle
Sonic Mega Collection
Sonic Adventure DX
Sonic Heroes (Multi)

Billy Hatcher
PSO Episode 1&2
PSO Episode 3
Sonic Gems Collection
Sonic Riders
 
Playstation 2
Astro Boy
SEGA Superstars
Phantasy Star Universe
Shadow The Hedgehog
(multi)
 
Gameboy Advance
Sonic Advance
Sonic Advance 2
Sonic Advance 3
Sonic Pinball Party
Sonic Battle
 
Nintendo DS
Puyo Pop Fever
Feel the Magic XX / XY
Rub Rabbits!!
Sonic Rush
 
NGPC
Sonic Pocket Adventure
 
N-Gage
SonicN
 
Game.com

Sonic Jam Game.com
 
Arcade
Sonic The Fighters
SEGASonic Arcade
 
Megadrive
Sonic The Hedgehog 2

Sonic The Hedgehog 3
Sonic Spinball
Sonic Crackers
Sonic CD v.510
Sonic CD v.712 & v.920
 
Game Gear
Sonic The Hedgehog
 
Sega Saturn
Sonic X-Treme
Sonic X-Treme 718
Sonic R: Trial Version
 
Dreamcast

Sonic Adventure 2: Trial

Sonic Adventure 2 Preview
 
Xbox

Sonic Heroes Alpha

Sonic Heroes E3 Demo
 
Xbox 360
Sonic Next-Gen
 
Gameboy Advance
Sonic Advance 3
 
Nintendo DS
Sonic DS - e3 Demo
 
Arcade
SEGASonic Arcade
 
Megadrive
Sonic The Hedgehog
Sonic The Hedgehog 2
Sonic The Hedgehog 3
Sonic & Knuckles
Sonic 3D: Flickies Island
Sonic Jam 6
 
Master System

Sonic Blast
 
Original Nintendo
Somari the Adventurer
Jurassic Boy 2
Family Kid
Sonic 3D Blast 5
Sonic 3D Blast 6
 
GameBoy/Advance
Jurassic Boy 2

Sonic 6
Sonic 3D Blast 5

Sonic Adventure 7
Sonic Advance
Sonic Advance 2
Sonic Advance 3

Sonic Pinball Party
Sonic Adventure 8
 
Super Nintendo

Sonic The Hedgehog 4
 
SoST Forum
FAQ
Time Capsule - SoStH
 
 
Videos

Due to the gargantuan size of some of these videos [Kikizo], I will link you to their respective pages to download the newest videos :)

Kikizo Videos

IGN Videos

Gamespot Videos