Sonic, the blue blur, the universe's quickest hedgehog, continues his escapades in this 4th episode of the Sonic The Hedgehog series. This time, he buddies up with his past enemy, Knuckles the Echidna, in order to get the better of the evil Dr. Eggman (a.k.a. Dr. Robotnik). At the end of Sonic The Hedgehog 3, Dr. Eggman's crowning orbital weapon for planetary domination, the Death Egg, was severely battered in an epic combat with Sonic. The Death Egg, losing power rapidly, hurtled back down to the major planet below and crash-landed on the cryptic Angel Island again. Now Sonic and Knuckles must put a stop to Dr. Eggman once and for all before Eggman and his no-goodniks find the enigma to Angel Island's aimless power, the Master Emerald. This one includes Lock-On Technology, which lets you to play as Knuckles in other Sonic games accessible from the Virtual Console, including Sonic The Hedgehog 2 and Sonic The Hedgehog 3, as long as these are downloaded into your Virtual Console library.