Sonic & Knuckles

However, in Sonic & Knuckles , unlike in Sonic 3 , the player chooses either Sonic or Knuckles at the title screen, Miles "Tails" Prower is not available to select, and the player cannot control two characters together. There is also no multiplayer mode or save feature. The player character moves through six levels , each divided into two acts. The first act of each level ends with a miniboss fight with one of Dr. Robotnik 's robots, while the second ends with a regular boss fight with Robotnik (or EggRobo in Knuckles's campaign). Sonic and Knuckles traverse levels differently; Sonic can jump higher and has access to unique shield abilities, whereas Knuckles can glide and climb most walls. The levels also include cutscenes that differ based on the character selected, as Sonic and Knuckles are opponents for most of the game. The game contains two types of bonus stages accessed by passing a checkpoint with at least 20 rings . The first type has Sonic or Knuckles orbit floating, glowing spheres, jetting off each one when a button is pressed, while a fence of light approaches from the bottom and will remove the player from the stage if touched. Collecting 50 rings in this stage earns the player a continue . The second type involves bouncing around a room with a slot machine in its center with the intention of winning extra lives and power-ups . Special Stages are entered by finding giant rings hidden in secret passageways: the player is placed in a 3D environment and must turn all of a number of blue spheres red by running through them, but must avoid all red spheres, including formerly blue ones. Yellow spheres bounce the player long distances, and white spheres with red stars on them make the player walk backward in the opposite direction. Completing a Special Stage earns the player a Chaos Emerald ; collecting all seven Emeralds allows the player to turn into Super Sonic or Super Knuckles, more powerful versions of the characters. Lock-on technology "Hyper Sonic" redirects here. For speed that exceeds five times the speed of sound, see Hypersonic speed . For other uses, see Hypersonic (disambiguation) . "Blue Sphere" redirects here. For the video game in the Star Ocean series, see Star Ocean: Blue Sphere . "Lock-on technology" redirects here. For other uses, see Lock-on . Sonic & Knuckles features "lock-on technology" that allows players to open the hatch on the cartridge and insert a second cartridge. When Sonic 3 is inserted, the player can play through both games as one, Sonic 3 & Knuckles . This features several changes to the games, such as slightly altered level layouts, the ability to play through Sonic 3 levels as Knuckles or Sonic & Knuckles levels as Tails, and the ability to save progress in Sonic & Knuckles levels. Additionally, combining the cartridges is the only way to collect "Super Emeralds", earned by accessing Special Stages in the Sonic & Knuckles levels after collecting all seven Chaos Emeralds from Sonic 3 . When all Super Emeralds have been collected, Sonic, Knuckles, and Tails can transform into Hyper Sonic, Hyper Knuckles, and Super Tails, each with unique abilities. Inserting Sonic 2 unlocks Knuckles the Echidna in Sonic the Hedgehog 2 , wherein the player can play Sonic 2 using Knuckles's abilities. If the player attaches any other Genesis game released prior to Sonic & Knuckles , a screen with Sonic, Tails, Knuckles, and Robotnik stating "No Way!" is displayed. From here, the player can also access a minigame based on Sonic 3 ' s and Sonic & Knuckles ' s Chaos Emerald Special Stages. The attached cartridge determines the Special Stage layout. If the player attaches the original Sonic the Hedgehog , they are able to access all of the possible variations of the special stages, each with a unique level number and corresponding password . This game is named Blue Sphere in Sonic Mega Collection and Blue Spheres in Sonic Origins .