So, the past themes were in a both versions of Sonic CD: Sega CD & Mega CD. Well, it sound like more of Mega CD version, because soundtrack here changes the mood, which depends, in which timeline you now (past, present, futures). And it's identical to present themes of Mega CD version. But the rumor's says, what America didn't like the soundtrack of Mega CD version, and at this time, they had their own studio for recording another bunch of soundtrack. And they did their own themes for present and futures. But honestly, I like this decision. Double the soundtrack - double the fun.
Game: Sonic CD (1993)
Game by: Sonic Team
Composer(s): Naofumi Hataya, Masafumi Ogata
Soundtrack: Tidal Tempest Past
This soundtrack has been extended for 12 minutes. Enjoy!
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