Ahh...Sonic CD, by far my Favorite Sonic game, I didn't had a Sega / Mega CD, but played it at the Sonic Gems Collection...so yeah, PAL with US sountrack, but anyways, I'm not here to review Gems Collection, but Sonic CD! Wooh!

Graphics: 6
Well, most of the sprites are ripped off from Sonic 1, but there are new ones, such as Super Peel Out sprites, and Mini Sonic sprites!

Sound: 10
I LOVE the music in Sonic CD, its great! But I preffer the Japanese sountrack over the US soundtrack...it gave me nightmares a a kid. (Talking about Boss music and Game Over...)
But still, its great!

Addictiveness: 8
I would replay the game all over again, but though, it lacks some replay value...it seriously lacks...but as I say again, I would replay it.

Story: 9
It's awesome, but a little copy cat-ish. I'll explain it.

Sonic heard about the rumors of a mysterious planet appearing above the Never Lake, a minature planet where the time flows freely, thanks to the Time Stones, as heard so, Sonic ran to the Never Lake, only to see the Little Planet covered in a metallic shell, and connected by a chain to the ground, and so, Sonic ran by the huge chain to the Little Planet. Enter: Amy Rose, who, also, is on Little Planet, as a tarrot card "fortune telled" Amy that she will meet with Sonic there, and right then, Metal Sonic kidnaps Amy! And so, Sonic must collect Time Stones, destroy the generators in the Past, defeat Metal Sonic and Robotnik (Didn't had any idea where to put Robotnik) and save Amy and the Little Planet!

Alright...time to explain why its a little copy cat-ish. Sonic must rescue a damsel-in-distress (Mario Bros. and Legend of Zelda anyone?) and defeat the evil...and why only a little copy cat-ish? Amy isn't a princess, Sonic must defeat Robotnik and Metal Sonic, not some weird creatures. And not the land, but a PLANET.

Depth: 5
As I explained before, theres no replay value, so you only need to complete the game once, and vu-a-la. BUT! There are 3 endings.
Bad Ending: Destroy only a couple of generators and/or collect less than 7 Time Stones
Good Ending: Destroy all the generators in the past, or just collect all the Time Stones.
Best Ending: Destroy all the generators and collect all the Time Stones.

Difficulty: 4
The game isn't so difficult, especially the bosses, but there is one boss that is challenging...Metal Sonic.
Every jump must be precise, you must run at the full speed, and don't let Metal Sonic get first, but thats only one boss.
The other variant about difficulty is time travel, you must hit a post and run at the maximum speed for 5 seconds to travel, easy, huh?
Actually, no, enter: level design/item placement, it makes it hard for you to time travel, for example, you are about to time travel, BOOM! You hit a wall, item box, etc. So its hard to time travel, but there are places that are just made for time travel, for example: a flat pathway with springs at the both ends, you run, run, run, and time travel!
Also, special stages are a little hard, its full pseudo-3D, not a half-pipe like what you got in Sonic 2, and when you run on water, you lose 10 seconds, and after Sonic runs too fast, it makes it harder, and harder, to hit the UFOs, so yeah...

Alright, that makes it for my review, and my overall rating is: 9.9!