Games

The storyline to Sonic Chaos revolves around Dr. Robotnik and his quest for world domination via the use of the mysterious Chaos Emeralds to create nuclear weapons and lasers (according to the North American instruction manual). Robotnik has stolen the Red Chaos Emerald, causing the other emeralds to "lose balance" and be transported to a parallel universe. As a result, South Island is now sinking into the ocean, and it is up to Sonic and Tails to save the island and foil Robotnik's plans of world domination.

Sonic 3 & Knuckles is a game that results when Sonic 3 is locked-on to Sonic & Knuckles via Lock-On Technology. It acts as one large combined game and all the levels from Sonic 3 and Sonic & Knuckles become available. There are several noticeable differences when playing the games combined. Knuckles is playable in the Sonic 3 levels and Tails becomes available in the Sonic & Knuckles levels. Also, all of the levels from both games are accessible, starting from Sonic 3. Once these levels are completed the Death Egg falls off screen intact instead of being destroyed, and then the play continues straight to the levels of Sonic & Knuckles. The final boss of Sonic 3 is also omitted for Sonic and Tails. After collecting all the Chaos Emeralds of Sonic 3 a new quest becomes available when entering the first special Stage in Mushroom Hill Zone which allows you to collect seven new Emeralds called "Super Emeralds". When these Emeralds are collected, Hidden Palace Zone will become available, and Sonic can transform into Hyper Sonic and Knuckles can transform into Hyper Knuckles. Tails has no Hyper form, but the Super Emeralds are needed for him to transform into Super Tails, as the Chaos Emeralds alone have no effect on him.

In single player mode, the player can choose to play solo, as either Sonic or Tails, or as a team, controlling Sonic, with the AI controlling Tails, which is the default configuration. Another player may take control of Tails at any time by using a controller plugged into port 2. The object of the game is to progress through the levels. In order to completely finish the game, seven Chaos Emeralds must also be collected from the special stages.

Knuckles in Sonic 2 is the resulting game when Sonic the Hedgehog 2 is locked onto Sonic & Knuckles with its passthrough port. Sonic is replaced by Knuckles and Tails is not playable whatsoever. The title screen features Knuckles also but removes the two player mode and options selections from it. This game is identical to Sonic 2 (aside from a few changes to make it more playable with Knuckles) but with Knuckles now playable instead of Sonic or Tails.