Knuckles' Chaotix: Part 2: Isolated Island
8After going through the Tutorial (or choosing to skip it when it begins), you continue on through the rest of the Zone you started in from Knuckles on his own up to him rescuing Espio from Eggman & Metal Sonic.
Isolated Island is nothing really more than a hand-warmer. There are no enemies or hazards here. Just you using Knuckles, Espio, and their Elastic Ring techniques in order to progress through 4 mini-Acts. Nothing here but door switches, Rings, and Item Monitors, such as those that make one of your characters huge or tiny.
These mini-Acts are represented as different times of day during Isolated Island, starting from the early morning and leading into the late night. Plotwise, this is just about Knuckles & Espio heading towards Eggman's newest base and looking for more of their friends to team up with against the mad doctor.
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At the end of the 4th mini-Act at night, you will properly finish the stage. If you get here with 50 Rings or more, a Giant Ring will appear, allowing one of your two characters to go through a Special Stage, just like in Sonic 1 & CD.
In these Special Stages, you must once again Get Blue Spheres. This time, they come in very small amounts and are scattered across very long 3D obstacle courses full of hazards and objects.
You will fail these Special Stages if you fall out of the course, or if your Rings run out, as they operate as your time limit.
To complete a Special Stage, you have to go through two rounds of getting enough of those Blue Spheres. If you fail a round, you'll have to repeat its course until you fulfill its quota before you can proceed onto the next round that has a different course layout.
Beating the second round rewards you with one of the 6 Chaos Rings of the game. You need them all for this game's Good Ending.
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This game was made by a lot of the same SEGA staff that not only worked on Sonic CD, but also Ristar. That explains the jump sound as well as the gorgeous art style. I don't ever feel this look from a regular Genesis Sonic game.
It also has one of the best Sonic soundtracks ever made, courtesy of ladies Mariko Nanba and Junko Shiratsu. The tracks even have names, with Isolated Island's being titled "Door Into Summer".