The Sonic Adventure 2 Demo that came with the Trial on Dreamcast. The only playable Characters you see are Sonic, Knuckles and Eggman. Some people say there were originally only these 3 playable characters. That would explain why Shadow, Rouge and Tails are just clones of them.
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Sonic Adventure 2 (ソニックアドベンチャー2 Sonikkuadobenchā tsū) is a platform game developed by Sonic Team...